So many problems.....Please help!!!!

I really hope you guys can help me, I dont know what else to do. Let me start out by listing some of the problems Ive been having.

--Computer sometimes shuts down and restarts right after starting it up. Seems to be happening more and more often.
--A trojan called PWSteal.Banker.B is detected by Norton but it is unable to repair, quarantine, or delete it.
--My desktop seems to have been hijacked. My picture was replaced by an ad saying something like "You're in danger". I traced the link and deleted all the files I found were involved but now Im left with a bare brownish desktop that I cannot change.
--When I start up the computer I get a message saying "Windows cannot find C:\WINDOWS\System32|services\exploit.exe. Make sure you typed the filename correctly and then try again". I click 'OK', then get the message, "Could not load or run "same as above" specified in the registry. Make sure the file exists on your computer or remove the reference to it in the registry."
--As soon as I connect to the internet I now get a message, "Windows Messenger. A newer version is available. You must install the newer version in order to continue". I have never used Windows Messenger, never even knew I had it. Why is this popping up now and what should I do?
--Periodically get a pop-up trying to load something called http://accu.acculoader.com.


These are the main ones I can think of right now off the top of my head, Ill post anything else wierd that I notice. The point is there are alot of problems going on with this computer.

Here is what I have done so far:
-Downloaded and started using Mozilla Firefox. Seem to be having so many problems with IE. I wouldnt even be able to post this if I were using IE. As soon as I hit the post button it would say something like IE has encountered a problem and needs to shut down. Ran sfc /scannow to see if this would help. Found nothing
-Updated and ran Norton AV, spy sweeper, CW Shredder, ad-aware, and spybot.
-Ran HijackThis. Here is my log. I hope someone here can help me. I know this was kinda long so I really appreciate you taking the time.

Edit by chaslang: turned HJT log into an attachment

 

I had the same exact thing happen to my desktop! My desktop is now gray and white and it flashes! Did you ever resolve that problem??