Suspected Blaster Worm.. Trojan..?

I recently downloaded a file from Mediafire, ( a 3rd Party Theme for Windows ) After a day or so, I began noticing while using Google chrome, I had a massively increased amount of popup ads, "YOU'VE WON!!! CLAIM NOW!!!!!" Windows, and even cases where when clicking Google search Result links, I'm redirected elsewhere, often a website that's filled with ads or bogus sweepstakes, etc. I downloaded AVG and ran a Safe-Mode system scan, and it showed that I had numerous Backdoor Trojans. (From what I've read, these particular viruses can resist removal when connected to the internet, so I disabled my WiFi switch before scanning)
-http://www.symantec.com/security_response/writeup.jsp?docid=2001-062614-1754-99

The part I'm worried about: is that my computer crashed while scanning (The sequence windows alerts you of when running "start shutdown -i" ) and it locked up, so I had no way of aborting it.
So.. my AVG scan was interrupted, of course. When I rebooted Windows, I got the error that %hs was missing from system.

(I flipped on that one, but eventually restored windows to before I even downloaded AVG)

The problem now is, I have just gotten rid of the Relevant Knowledge spyware-whatever; and i would REALLY like to get rid of what AVG refers to as having Generic Backdoor Trojans.. (one of them.. Generic 27 or something, was found in iTunes... ) but I have no means of purchasing antivirus software, my Norton Subscription ended, and I really don't want my computer full of Trojans (My last computer was ruined by my brother, who likes to play with Powershell)
I also would like to know a legitimate programm to clean my registry of errors and such.. I don't trust any programs that I've found so far. I attempted to do it manually, but regedit crashed every time I opened it, even with elevated control >.<

Thanks. Any advice or help is appreciated :)

I've used Malwarebytes.. After the scan, it asks for a subscription before removing any detected malicious data...
SAS is down.. I tried last night and their server is down.

I would use Norton Power Eraser; but it requires Internet conection to use, and I don't have internet except on occasion.

[QUOTE=Kaoruko;1876883]
SAS is down.. I tried last night and their server is down.
/QUOTE]

My bad. It isn't now.

I've just ran Wise registry Cleaner a few times, thinning away the errors with each scan. I re-downloaded Malaware Bytes, but I have yet to scan just yet. (I'm quite busy; using multiple programs during a virus scan can be an arduous task.)
AVG left behind some data after my restore, but I deleted each of them from both Program files (x86) and just now from the registry, but the application and it's .dll files were all removed during System Recovery (why it was still withi the reg, I don't know...)

So far, I have yet to have any trouble with ads like I had before, but even now I still get the inline ad that shows multiple "download" 'images' (all one embed.. doesn't matter where you hover; url never changes) for Ilivid or something-or other.


Anyway, for now, I think things are returning back to what I called normal.

Thanks for the input :)

Oh, should I go on and remove Norton Internet security? I'm not 100% on if it will conflict with Malwarebytes or not.