I have Windows XP SP2. Every so often, the system suddenly stops responding to mouse clicks on the taskbar or desktop, although it will still respond to mouse clicks within an open program. If I press CTRL-ALT-DEL to bring up the Task Manager, it starts responding again (until it stops again.) I remember having this problem before a long time ago, but I don’t remember what I did to fix it. VirusScan doesn’t show any viruses and AdAware doesn’t show any spyware.
Sounds to me like your copy of explorer.exe may be corrupt. Try running the System File Checker (Start > Run > sfc /scannow)… it’ll check all your system files and replace any that need fixin’.
I ran it, but it didn’t seem to show anything wrong.
Hmm, has it always done that, or did it seem to start all of a sudden? Do you remember installing any new hardware or software around the time it began?