error en la instalación

Hola a todos
intento instalar sql 2005 en una máquina donde ya hay sql2000 aunque creo
una instancia nueva, cuando está instalando las herramientas, me dice que hay
un error y se cierra. En el fichero Core.log aparece este mensaje:

Error: Action "LaunchLocalBootstrapAction" threw an exception during
execution. Error information reported during run:
"C:\Archivos de programa\Microsoft SQL Server\90\Setup Bootstrap\setup.exe"
finished and returned: 1603
Aborting queue processing as nested installer has completed
Message pump returning: 1603

y en el fichero Core(local).log:

Skipped: UninstallForRS2000Action
Skipped: Action "UninstallForRS2000Action" was not run. Information
reported during analysis:
Action: "UninstallForRS2000Action" will be skipped due to the following
condition:
Condition "Action: InstallRSAction was skipped." returned true.
Running: InstallToolsAction.10 at: 2007/4/26 9:23:54
Error: Action "InstallToolsAction.10" threw an exception during execution.
Error information reported during run:
Target collection includes the local machine.
Fatal Exception caught while installing package: "10"
Error Code: 0x80070002 (2)
Windows Error Text: El sistema no puede hallar el archivo especificado.

Source File Name: sqlchaining\sqlprereqpackagemutator.cpp
Compiler Timestamp: Tue Aug 9 01:14:20 2005
Function Name: sqls::SqlPreReqPackageMutator::modifyRequest
Source Line Number: 196

- Context --
sqls::InstallPackageAction::perform

WinException caught while installing package. : 1603
Error Code: 0x80070643 (1603)
Windows Error Text: Error grave durante la instalación.

Source File Name: packageengine\installpackageaction.cpp
Compiler Timestamp: Fri Jul 1 01:28:25 2005
Function Name: sqls::InstallPackageAction::perform
Source Line Number: 167

- Context --
sqls::InstallPackageAction::perform

Error: Failed to add file :"C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\Files\SQLSetup0001_MQ1_.NET Framework Upgrade
Advisor.log" to cab file : "C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\SqlSetup0001.cab" Error Code : 2
Error: Failed to add file :"C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\Files\SQLSetup0001_MQ1_.NET Framework Upgrade
Advisor LangPack.log" to cab file : "C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\SqlSetup0001.cab" Error Code : 2
Error: Failed to add file :"C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\Files\SQLSetup0001_MQ1_.NET Framework Windows
Installer.log" to cab file : "C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\SqlSetup0001.cab" Error Code : 2
Error: Failed to add file :"C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\Files\SQLSetup0001_MQ1_.NET Framework Windows
Installer LangPack.log" to cab file : "C:\Archivos de programa\Microsoft SQL
Server\90\Setup Bootstrap\LOG\SqlSetup0001.cab" Error Code : 2
Running: UploadDrWatsonLogAction at: 2007/4/26 9:24:7
Message pump returning: 1603

¿Tenéis idea de a qué puede ser debido y cómo arreglarlo?

Gracias por vuestra atención.
Saludos