Getting rid of malware screen theme

From: Martin (nagasml_at_netscape.net)
Date: 07/31/05 

Date: 30 Jul 2005 18:01:13 -0700

Just as I was ending an internet session, I found that the opening
"wallpaper image" - or maybe 'theme' is the proper word? - had been
hijacked by an unwanted ad for a spy removal ware called PSguard. So
far the functions are not affected, but it's very irritating - the
screen jet black against an intrusive message - and a quick check on
the web confirmed it's a recent malware.
However it seems, of course, to have blocked the function for changing
screen wallpaper, so I can't shuck it out that way. How do I get around
this?

The PC runs on Win XP with Norton firewall and Antivirus, it's not part
of a LAN, and otherwise it's free of manifest virus problems.

note: I just checked the activities manager and there are two processes
which could be suspect: NPROTECT.EXE and NPFMNTOR.EXE (both using
several megs of memory right now) Those two normally belong with
Norton, but a spyware or adware could pose under these names, couldn't
it? They can't be closed down, however.

any tips appreciated

 Martin, Sweden