1. Back up all your data.... Once that's done, scan it on another machine that you know is clean....
2. Do a low level format of your hard drive.. This is the only absolute way to fully format and "zero" out every sector of the drive.. Reformatting with windows never formats the
the boot sector(where viruses can reside)..
3. Reinstall your OS and be sure to get all the updates..
As others have said here, AVG is junk and is inherently known for lots of falls positives and truly fails to remove or block anything.. If you are looking for something free,
Antivir
http://www.free-av.com/en/trialpay_download/1/avira_antivir_personal__free_antivirus.html is absolutely the best thing you can get that doesn't expire after
30 days.. It's made in Germany.. Germans make good stuff.. I've using it for years and have never ever once got an infection ever.. This uses very little resources and runs quietly
in the background not inhibiting performance one bit. The only issue is that every time it updates, it'll give you a little advertisement to buy the registered version.. However, I disable
auto update while playing AH and this neutralizes this issues..
After installing your antivirus software, you'll want to download and install SpywareBlaster
http://www.javacoolsoftware.com/spywareblaster.html.
This will actually prevent malware from being installed on your machine.. It's not a scanner and it only needs to be run to update (about every 2 weeks)..
It makes changes to your registry that blocks any malware from installing itself on your machine.. I consider this a very important part of my defense..
Next, you'll want to install a software firewall such as Sunbelt
http://www.sunbeltsoftware.com/Home-Home-Office/Sunbelt-Personal-Firewall/.. Again
this is free to use.. They give you 30 days of the Professional Version which downgrades to the free version after that.. But the free version works great!
The Professional Version has features you'll probably never use.. Anyhow, this is another good one that uses very little resources..
Lastly, you need to be behind a router with a firewall....Absolutely.. Even if you just connect 1 computer to it.. The hardware firewall in a router is detrimental
to your PC's security as well as the any others that are on your network.. Be sure that the wireless security and router login setup is taken care of as well..
AMENDMENT!!
Don't low level format your drive if you are going to use a restore partition such as included with Dell, HP, etc..
That is unless you have the a physical copy of the restore disks..