Okay, a while back my computer got infected with a virus.  it was malware's PsGuard (or something along those lines.)  My Norton had just ran out so I downloaded a trial Panda which got rid of mostly everything.  However, there is still this odd blank box on my desktop that flashes from black to grey periodically.  This first appeared when I got the virus or whatever it was, but now it's sitll there and it's not only a nuisance, but I don't want it to be doing anything bad to my computer.  I can't get rid of it and when I Ctl+Alt+delete, there are no strange programs running or anyhting.  Please someone help.Virus scanners
AVG Free
-- Anti virus scanner
Trend Micro Housecall
-- Online anti virus scanner.

Anti spy/malware
Microsoft Antispyware
-- Anti spyware scanner. Windows XP Home and Professional only.
Spybot Search & Destroy
-- Anti spyware scanner
Adaware SE Personal
-- Anti spyware scanner

Firewalls
Use both a hardware and software firewall.
Be ADVISED as dual software firewalls may CAUSE problems

ZoneAlarm Free
-- Free firewall - more user friendly
Sygate Personal
-- Free firewall - more configuration options

Removal tools
The following files are not substitutes for the ones described above.
They are either diagnostic tools or removal tools for malware of a certain kind

HijackThis
-- Manual malware REMOVER. Post the HijackThis log generated only if requested!
McAfee Stinger
-- Virus removal tool. No substitute for a fully functional virus scanner!
CWshredder
-- CoolWebSearch removal tool. Widely known and persistant Hijacker.Right click & check it's properties?
Just to be sure...
Free online virus scan
http://www.pandasoftware.com/activescan/
Free online spyware scan
http://www.pandasoftware.com/products/spyxposer/com/spyxposer_principal.htm
If all else fails delete it with killbox.exe (GOOGLE for it)no spyware or antivirus scans are gettin rid of it... when i check it's properties it says its a URL and the address is: file://C:\WINDOWS\desktop.html        What do your scanners detect? You're not being very specific.