Updates to one of my FireFox 3 add ons was spiked!

OK, because I was gone for a week, I noticed, rather I was reminded by FireFox 3 that there were now updates to the add ons I had installed on it. So I did a full add on update, by selecting every add on on the updates section that Firefox's add ons window showed.

After it finished, I resumed my computer session which includes my log in time here at RomUlation.

Now, when I started up my PC today, it couldn't fully start up, it kept rebooting 'til it got to my PC desktop area bit. It again rebooted for one last time until it finally started up in a stable fashion (it's running stable as you read this).

I do a deep AVG scan by setting scan mode to "slow scan", after finishing, I get goosebumps as AVG reports that there is nothing wrong, no infections whatsoever. ???

I uninstall FireFox 3 & all it's add ons as that's the only thing I did "new" to my system yesterday. I even deleted all of it's directory associations that are left behind when you uninstall it, just to make sure.

Now I don't know what to do?

Here are all the add ons I used, but I don't know which of it was the spiked add on:

AdBlock Plus - couldn't be as you guys swear by this
Flashgot - same as above, right?
Cool Iris (PicLens) - actually the update wasn't compatible with FireFox 3.0.1
AVG extensions
Aeon theme
DownloadHelper
Download status bar
Flagfox
Undo Closed Tabs
Colorful Tabs
Fast Dial
Winamp toolbar
Google preview

The ones after the AVG extensions are the ones I suspect, but which one?

For now, I'm using "lame old" IE7

 

I suggest doing a HijackThis test before making sure it's the Firefox update that is the problem. Download it, boot into safe mode, run, save results. Post on a PC forum.

 

Well I updated my Adblock Plus ages ago, and now all the webpages and settings for everything reset when I boot up, so that's why my Chatzilla is now always "User". Not anything to do with your problem, but yeah, similar.

 

I did get hijackthis & did a test using it on safe mode, most of the things it listed were familiar apps & programs. The only things I wasn't familiar with are the registry & system32 bits

UPDATE:

Just so to elaborate on the issue, I did some google search research on the matter, & yes, this wasn't the first time this happened. Apparently, there were other instances where a Firefox add on or update was spiked with harmful code.

Using my system as bait by re installing FireFox 3 then one by one re installing each add on, I found which of my add ons had it, it was the latest version of "Fast Dial". AVG can't detect it, but Malwarebytes' Anti-malware found it, a virus named hijack (start up).

I'm currently still on IE7 but will soon go back to FireFox 3 right after I reformat & re install Windows XP (I could just use regedit to fix my registry, but I'm not knowledgeable in that area).