Error message in XP Home

For the last couple of days a pop up black window appears on my screen
every twenty minutes with the following message:
C:\WINDOWS\TEMP\WIN*.*~1.EXE

I have uninstalled Norton Antivirus 2005, and have replaced it with
Panda Internet Security 2007, but none of them detects any viruses on
my PC.

Could you please tell me how to solve this problem?

.

Loading