Trojan - Browser Hacker plz help!

I am having a load of problems right now. It doesn't seem to be getting any worse but I cannot seem to get rid of any of them. I first noticed that clicking online links was redirecting me to random advertisements and grew very frustrated. I'm using AVG Free and initially only had Malwarebytes' Anti Malware. The first indication that I had a virus/trojan/whatever was when this fake spyware program called MS Antispyware 2009 popped up. Since then my AVG resident shield has recognized (in this order): Trojan.Vundo, Trojan generic10 (something along those lines), and Trojan BackDoor.SmallX.VX. I d/l'ed VundoFix which everytime I ran it did not detect any vundo. Upon many scans with different programs the Generic10 no longer shows up. And now, BackDoor.SmallX.VX appears to be the only one that continually pops up (particularly whenever I try to run ComboFix).

I followed a similar thread here on Major Geeks (username 'Infected', title 'Browser Hijacker') and following some of the steps given there I have since dl'ed SUPERAntiSpyware, Avenger, and CCleaner (I already had HijackThis). I could only run ComboFix in safe mode and it yielded no results. If I try to run it normally I get an error report about a 'prep.com'. I have no idea what this means other than it might be the virus preventing me from running this program.

I also experience an error upon every startup that says: RUNDLL "Error loading C:\DOCUME~1\Brian\STARTM~1\Programs\Startup\ChkDisk.dll". I've noticed a Startup Item called ChkDsk, but the "ChkDisk" seems strange and I don't know what this error is referring to.

Finally, and most recently, I noticed a process called 'System' in task manager. Not 'system.exe' but just 'System'. I've never seen that before and it is using a considerable amount of Memory (relative to any other processes I have running).

I have Service Pack 3, and my Java is updated.

If you could help me with any or all of these problems that would be awesome. I'm moderately to highly computer illiterate, so the more specific instructions the better. I've had a friend help me get to this point and he recommended talking to an expert.

THANK YOU

 

Oh, another note, I cannot close the process 'System'. I click End Process and nothing happens...a little disconcerting.

 

Here are my SuperAntiSpyware, Malwarebytes, and MGTools logs.

 

I'm still unable to run ComboFix in normal mode. The following log is from ComboFix when I ran it in safe mode a little more than a week ago. I'm also unable to uninstall CF. In normal mode when I try 'Run > combofix /u' I encounter the previously mentioned error with a 'prep.com' and the program closes. When I tried uninstalling CF in safe mode it tells me the program has been successfully uninstalled, however the desktop icon remains there and it remains functional (clicking it results in CF loading up and running). Here is the log regardless:

 

I don't seem to be having any problems, however if every time I tried to run ComboFix I got the warning about BackDoor.SmallX.VX trojan doesn't that mean my computer is still infected with something?

Perhaps this is a topic for a different thread, but I still cannot figure anything out about the "System" (no ".exe") that shows up in my Task Manager. I don't think it is causing harm to my CPU but it is a new development and seems rather unnecessary in the amount of memory it is using.

Thanks for the help

 

"System" shows up as both the image name and user name. I've talked to a friend who also has this process running, but his is using a very small amount of memory, whereas mine is the highest mem usage when all windows are closed (about 60,000k; firefox is about 100,000k when open). I'm more or less just curious why it's using the amount of memory it is and if I can change that.

AVG resident shield is reporting Trojan BackDoor.SmallX.VX. But either way, ComboFix cannot run because it closes itself out with a separate error message saying "prep.com has experienced an error and needs to shut down" - something to that effect. The prep.com error always appears first. Once I close that box that is when the resident shield reports the BackDoor message. So clearly, something is preventing combofix from being run, no? And even if it's not necessary for me to run combofix, the fact that something won't allow that program to open implies I have some sort of virus, does it not?

 

Ok, I'll try to download it and run it with AVG disabled - although I think the first time I ran combofix I had AVG disabled and I ended up with the same problem. "Service" was not a process I was concerned about, it was "System". I realize it's not malware but I was uncertain why it was suddenly taking up so much mem usage. This is probably a topic for a different thread. Thanks for your help.