I can't find anything on this. If this is a recent issue, try using System
Restore to take you back to a time prior to when this began.
If that doesn't resolve it, try Ad Aware:
www.lavasoftusa.com
Also, you might check the error log to see if there are any clearer
notations there. Open Control Panel, open Administrative Tools, open Event
Viewer, look for any errors that correspond to when this error appears,
double click the error, the information contained within may give a clue as
to the source of the error.
Additionally you might run a virus scan. I'd start backing things up
because while a lot of people are starting to have this problem, no one has
been able to trace the source so your only out may be to format do a new,
clean install of XP.