Disk Cleanup problem

In start/programs/accessories/system tools there is Disk clean up. But when
I try to use it I get the message:
Disk Space Cleanup Manager for Windows has encountered a problem and needs
to close. We are sorry for the inconvenience.

When I click to see the error I find:
Error signature:
AppName: cleanmgr.exe AppVer: 6.0.2900.2180 ModName: unknown
ModVer: 0.0.0.0 Offset: 10001aaa

It used to work about a month ago, I don't know what happened. I have the
idea it started after downloading some windows updates but i'm not sure
about that.
Can someone help me? I have winxp Home edition.

Thank you.
Dimitris