Windows update no descarga actualizaciones. error c015001a

Hola, porfavor, necesito que alguien me ayude a solucionar este problema:

Tengo windows vista, restauré el sistema y desde entonces no se me instala
ninguna actualización de windows update.

Pulso buscar actualizaciones,las busca...
aparece un nuevo aviso de "instalar nuevo software de windows update"...
pulso instalar. pone que descarga e instala actualizaciones, pero después de
un rato vuelve a aparecer el mismo aviso del principio "buscar
actualizaciones para el equipo".
Repites los pasos varias veces y acaba apareciendo el error Código: C015001A
y no encuentro como solucionarlo.

os dejo el windowsupdate.log:

2007-11-11 11:23:38:296 1108 9bc AU Triggering AU detection through
DetectNow API
2007-11-11 11:23:38:296 1108 9bc AU Triggering Online detection (interactive)
2007-11-11 11:23:38:296 1108 f80 AU #############
2007-11-11 11:23:38:296 1108 f80 AU ## START ## AU: Search for updates
2007-11-11 11:23:38:296 1108 f80 AU #########
2007-11-11 11:23:38:296 1108 f80 AU <<## SUBMITTED ## AU: Search for updates
[CallId = {6E5B99AB-25D6-4685-B99D-2A6A5977BC27}]
2007-11-11 11:23:38:296 1108 e1c Agent *************
2007-11-11 11:23:38:296 1108 e1c Agent ** START ** Agent: Finding updates
[CallerId = AutomaticUpdates]
2007-11-11 11:23:38:296 1108 e1c Agent *********
2007-11-11 11:23:38:296 1108 e1c Setup Checking for agent SelfUpdate
2007-11-11 11:23:38:296 1108 e1c Setup Client version: Core: 6.0.6000.16386
Aux: 7.0.6000.381
2007-11-11 11:23:40:808 1108 e1c Setup Determining whether a new setup
handler needs to be downloaded
2007-11-11 11:23:40:808 1108 e1c Setup SelfUpdate handler update NOT
required: Current version: 7.0.6000.381, required version: 7.0.6000.381
2007-11-11 11:23:40:808 1108 e1c Setup Evaluating applicability of setup
package "WUClient-SelfUpdate-ActiveX~31bf3856ad364e35~x86~~7.0.6000.381"
2007-11-11 11:23:40:917 1108 e1c Setup Setup package
"WUClient-SelfUpdate-ActiveX~31bf3856ad364e35~x86~~7.0.6000.381" is already
installed.
2007-11-11 11:23:40:917 1108 e1c Setup Evaluating applicability of setup
package "WUClient-SelfUpdate-Aux-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381"
2007-11-11 11:23:41:822 1108 e1c Setup Setup package
"WUClient-SelfUpdate-Aux-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381" is
already installed.
2007-11-11 11:23:41:822 1108 e1c Setup Evaluating applicability of setup
package "WUClient-SelfUpdate-Core-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381"
2007-11-11 11:23:42:056 1108 e1c Setup Setup package
"WUClient-SelfUpdate-Core-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381" is
applicable and needs to be downloaded.
2007-11-11 11:23:42:056 1108 e1c Setup SelfUpdate check completed.
SelfUpdate is required.
2007-11-11 11:23:42:056 1108 e1c Setup Downloading binaries required for
SelfUpdate
2007-11-11 11:23:44:770 1108 e1c Setup Downloading setup package
"WUClient-SelfUpdate-Core-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381"
2007-11-11 11:23:44:770 1108 e1c Setup Downloading setup package
WUClient-SelfUpdate-Core-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381.cab from
http://download.windowsupdate.com/v.../x86/Vista
2007-11-11 11:24:05:908 1108 e1c Setup Staging setup package
"WUClient-SelfUpdate-Core-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381"
2007-11-11 11:24:50:961 1108 e1c Setup WARNING: CBS staging operation
failed, error = 0xC015001A
2007-11-11 11:24:50:961 1108 e1c Setup FATAL: Failed to stage setup package
"WUClient-SelfUpdate-Core-TopLevel~31bf3856ad364e35~x86~~7.0.6000.381", error
= 0xC015001A
2007-11-11 11:24:50:961 1108 e1c Setup WARNING: Failed to stage applicable
setup packages, error = 0xC015001A
2007-11-11 11:24:50:961 1108 e1c Setup FATAL: Downloading binaries for
SelfUpdate failed, err = 0xC015001A
2007-11-11 11:24:50:961 1108 e1c Agent * WARNING: Skipping scan,
self-update check returned 0xC015001A
2007-11-11 11:24:51:133 1108 e1c Agent * WARNING: Exit code = 0xC015001A
2007-11-11 11:24:51:133 1108 e1c Agent *********
2007-11-11 11:24:51:133 1108 e1c Agent ** END ** Agent: Finding updates
[CallerId = AutomaticUpdates]
2007-11-11 11:24:51:133 1108 e1c Agent *************
2007-11-11 11:24:51:133 1108 e1c Agent WARNING: WU client failed Searching
for update with error 0xc015001a
2007-11-11 11:24:51:133 1108 e1c AU >>## RESUMED ## AU: Search for updates
[CallId = {6E5B99AB-25D6-4685-B99D-2A6A5977BC27}]
2007-11-11 11:24:51:133 1108 e1c AU # WARNING: Search callback failed,
result = 0xC015001A
2007-11-11 11:24:51:133 1108 e1c AU # WARNING: Failed to find updates with
error code C015001A
2007-11-11 11:24:51:133 1108 e1c AU #########
2007-11-11 11:24:51:133 1108 e1c AU ## END ## AU: Search for updates
[CallId = {6E5B99AB-25D6-4685-B99D-2A6A5977BC27}]
2007-11-11 11:24:51:133 1108 e1c AU #############
2007-11-11 11:24:51:133 1108 e1c AU Need to show Unable to Detect notification
2007-11-11 11:24:51:133 1108 e1c AU AU setting next detection timeout to
2007-11-11 15:24:51
2007-11-11 11:24:51:133 1108 e1c AU Setting AU scheduled install time to
2007-11-12 02:00:00
2007-11-11 11:24:55:969 1108 118 Report REPORT EVENT:
{CD10BD25-7A49-41D9-B0FF-5DD2C82B40D1} 2007-11-11
11:24:50:961+0100 1 161 101 {E2FF4526-97D7-4926-8E75-295DBA39C6BF} 1 c015001a SelfUpdate Failure Content Download Error: Download failed.
2007-11-11 12:00:30:438 1108 c60 Report Uploading 2 events using cached
cookie, reporting URL =
http://stats.update.microsoft.com/R...rvice.asmx
2007-11-11 12:00:45:680 1108 c60 Report Reporter successfully uploaded 2
events.
2007-11-11 12:10:10:773 1108 e38 DnldMgr *********** DnldMgr: Downloading
regulation Odf ***********
2007-11-11 12:10:10:773 1108 e38 DnldMgr * ServiceId =
{9482F4B4-E343-43B6-B170-9A65BC822C77}
2007-11-11 12:10:10:773 1108 e38 DnldMgr * URL =
http://www.update.microsoft.com/odf/v6odf.xml
2007-11-11 12:10:24:720 1108 e38 DnldMgr * Odf parameters...
2007-11-11 12:10:24:720 1108 e38 DnldMgr * Refresh interval: 2
2007-11-11 12:10:24:720 1108 e38 DnldMgr * Accept rate high: 10000
2007-11-11 12:10:24:720 1108 e38 DnldMgr * Accept rate normal: 10000
2007-11-11 12:10:24:720 1108 e38 DnldMgr * Accept rate low: 0
2007-11-11 12:10:24:720 1108 e38 DnldMgr *********** DnldMgr: Downloading
regulation Odf ***********
2007-11-11 12:10:24:720 1108 e38 DnldMgr * ServiceId =
{7971F918-A847-4430-9279-4A52D1EFE18D}
2007-11-11 12:10:24:720 1108 e38 DnldMgr * URL =
http://www.update.microsoft.com/odf/v6odf.xml
2007-11-11 12:10:25:047 1108 e38 DnldMgr * Odf parameters...
2007-11-11 12:10:25:047 1108 e38 DnldMgr * Refresh interval: 2
2007-11-11 12:10:25:047 1108 e38 DnldMgr * Accept rate high: 10000
2007-11-11 12:10:25:047 1108 e38 DnldMgr * Accept rate normal: 10000
2007-11-11 12:10:25:047 1108 e38 DnldMgr * Accept rate low: 0
2007-11-11 12:10:25:078 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:078 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:110 1108 e38 DnldMgr *********** DnldMgr: New download
job [UpdateId = {DD6A0A94-A709-480C-AE67-A4AB1D27014D}.101] ***********
2007-11-11 12:10:25:110 1108 e38 DnldMgr * Update is not allowed to
download due to regulation.
2007-11-11 12:10:25:110 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:110 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:125 1108 e38 DnldMgr *********** DnldMgr: New download
job [UpdateId = {EC1C81F1-1DA8-4629-9AF9-7509F876D9D2}.101] ***********
2007-11-11 12:10:25:125 1108 e38 DnldMgr * Update is not allowed to
download due to regulation.
2007-11-11 12:10:25:125 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:141 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:172 1108 e38 DnldMgr *********** DnldMgr: New download
job [UpdateId = {BDE9F941-456F-44FB-A87F-B5EAC1FEA2E6}.101] ***********
2007-11-11 12:10:25:172 1108 e38 DnldMgr * Update is not allowed to
download due to regulation.
2007-11-11 12:10:25:172 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:172 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:203 1108 e38 DnldMgr *********** DnldMgr: New download
job [UpdateId = {DD6A0A94-A709-480C-AE67-A4AB1D27014D}.101] ***********
2007-11-11 12:10:25:203 1108 e38 DnldMgr * Update is not allowed to
download due to regulation.
2007-11-11 12:10:25:203 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:203 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:234 1108 e38 DnldMgr *********** DnldMgr: New download
job [UpdateId = {EC1C81F1-1DA8-4629-9AF9-7509F876D9D2}.101] ***********
2007-11-11 12:10:25:234 1108 e38 DnldMgr * Update is not allowed to
download due to regulation.
2007-11-11 12:10:25:234 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:234 1108 e38 Service WARNING: GetUserTokenFromSessionId
failed with error 800703f0 for session 0
2007-11-11 12:10:25:250 1108 e38 DnldMgr *********** DnldMgr: New download
job [UpdateId = {BDE9F941-456F-44FB-A87F-B5EAC1FEA2E6}.101] ***********
2007-11-11 12:10:25:250 1108 e38 DnldMgr * Update is not allowed to
download due to regulation.