I don't know what happens in my computer

Hi mates,

When a finish my session of Windows XP, I see a window saying that
the process explorer.exe is blocked and it needs to terminate. When I
press the Finalize process button, Another window appears again, with
the same problem but with Connections Tray process. If I do not press
the button, it will finalize in a few minutes.

I note that my programs run so slow. And, if I see the list of the
processes, the explorer.exe gains KB little by little until. Sometimes
it exceeds the 100 MB in memory.

My antivirus doesn't say anything of viruses or troyans that
I could have possibly.

What's happen to my computer. When the explorer.exe grows in KBytes,
isn't because i have many windows open.

I can read replies in english or spanish. Thanks.

Marcelo.