OK, this is what you need to do and it will take some time on your part.
First off, let me say, do not reinstall your Windows OS, that is only going to lead to other issues. You only do that as a last resort.
Downloading and scanning with AVG was a good thing. However, I hope that you do not have another anti-virus (AV) software installed on your computer. You can only have one AV installed at a time, they will conflict and neither will work properly, if at all. Now the new AVG Free will pick up some trojan horses and tracking cookies, but it is not meant to be a stand alone anti-spyware software. It is to track down and get rid of viruses, completely different "animals".
Now that you have your AV covered, you will need to cover anti-spyware software. Unlike AV's, you will need more than one. Each scans using a different method and will pick up different things. You will need to download, install, and update all of these softwares, and then scan your computer with all of them. This is going to take a while.
Here they are (all are free and they are all good)...
Spybot Search and Destroy
http://www.download.com/Spybot-Search-Destroy/3000-8022-10122137.html
Adaware 2008
http://www.download.com/Ad-Aware-2008/3000-8022_4-10045910.html
Windows Defender
http://www.microsoft.com/windows/products/winfamily/defender/default.mspx
Like I said, download, install, and update all of their definitions, and then scan your computer with them.
This will get rid of your pop-ups.
Another software that you should have is Spyware Blaster. I am assuming that you are using IE or Firefox as a browser. It is only good at stopping ActiveX based malware, but it is the best out there. Just download, install, update, and enable all of the protection. No scanning is required.
http://www.download.com/SpywareBlaster/3000-8022_4-10196637.html
Now this is not a one time deal. In order to keep your computer healthy, you will need to scan with all of these software, at the very least, once a month. Once a week is better. I know it is a pain, but it needs to be done regularly.
Ccleaner, which you already used, is not going to fix your problem but it is a real good general maintenance software that you should continue to use.
Other things to do in order to keep your computer safe.
- Make sure that your Firewall is turned on and updated (VERY IMPORTANT)
- Upgrade to IE7, if you are still using IE6. Firefox is even better. You can have both browsers installed and will have no problems.
There are other things that will make your computer faster, but that is for another time. Contact me should you want the details.
Good Luck!!!!
Made on a Mac!!!!