having problems with my new PC

My problems seem to be different kinds of symptoms. Norton Internet Secruity and Anit-Virus are not handeling things well so I suspect if I have something that it is intentionally making things harder for that program. I tried several times to run them both on Safe mode and they never opened, they crashed before I could see anything. Also during Safe mode I couldn't run the remote anti-virus check on the Symantec website, it wouldn't load. Overall PC performance is down, big suprise. Another aparrent problem comes up with my thumbnails view made by Windows XP. When I get to certain folders set to the "thumbnails" view they begin to generate the thumbnails as normal, but then the folder crashes closing any other folders that were open too. All my programs that are on at the time keep running though.

Programs I've run on the PC have found W32.Sober and Istbar. The problem with those is that after their intial detection they're not found again and I really don't think the programs that found them deleted or repaired them. I've run the symantec repair programs for both of them right after detection, but neither program found anything. There's also something strange going on with the file ptipbmf.dll in my C:\Windows\System32 folder. Avast! said it was either a virus itself or it was infected by a virus I believe.

I've already run a large amount of anti-spyware and anti-virus programs on my PC in safe mode:

Trend Micro's Free Online Virus Scan
McAfee AVERT Stinger
Ad-Aware SE
Registry Mechanic
Spyware Doctor
Ad-Aware VX2 Cleaner Plug-In
CCleaner
Spybot
SpywareBlaster
CWShredder.
Kill2me
about:Buster
HSRemove
avast! Virus Cleaner Tool
AntiVir
AVG personal
a-squared