Have you ever click on a link or open a web page and got that annoying audio and message about your computer is infected. They give you an 800 number to call so they can clean your computer. First don't call these people, this is a scam and in some case can lead to identity theft if you let them into your computer to poke around in it. Most people think at this time they need to call IT support because there AV didn't catch this and now they can't get to different web pages because this message always comes up. However there may be ways for you to get rid of this annoyance without calling IT Support. One way is to clear your internet browser cache. Since there are many browsers and they are done differently I would recommend using what some IT professionals use and it is a free software that is available to you. The software I use is called TFC Total File Cleaner (link below) This will clean your temporary files off your computer from the temp location, from all the browser, system and java cache.
Should you still have pop-ups after this then I would recommend running AdwCleaner (Adware Cleaner) This software is also free (link below) and will do a bit deeper scanning looking for adware that is running and that is hiding in common file areas. However if you are running AVG you will need to look at the registry entries it finds, on the registry tab, and look for entries that have AVG in them. you will want to uncheck these entries before you hit the clean button.
There is a third program that you can use if you are still having the pop-ups after running the first to programs and that program is TDSSKiller (link below). This program is designed to look for root kits that hide in the Master Boot Record (MBR). Sometimes malicious software can hide itself in the master boot record and not all Anti-Virus software checks for this. This program will check and if it finds anything you have options to Cure, Delete or quarantine what it finds. If you are unsure which option to choose I would recommend to quarantine what it finds.
If you are still having pop-up issues after this I would recommend IT Support at this time as your issue will need help will require professional help.
The links below will start the download automatically
AdwCleaner (If you have a slow PC or internet you may have to wait a minute or to before the download starts for AdwCleaner)
TDSSKiller (If you have a slow PC or internet you may have to wait a minute or to before the download starts for TDSSKiller)