I've been running at home for almost nine years now and have never had a problem with it. Yes, it will pop up on some web pages if a trojans or viri try to download. I have installed it in a few business environments with huge success rates. Even at my work where Sophos is a mandated company standard, I run AVG instead. I've run almost a dozen different AV programs and have had fewer issues with AVG and never has it let a virus through. No program can protect against a person who infects their machine because of lack of patching and general common sense with the web and email. And it's free for home use. The internet security goes a few steps beyond normal protection.
If yours has been freezing up completely, backup everything to USB drive or dvd now. It's not always the operating system with the problem. Your hard drive may be on it's way out. If it is XP acting up, run msconfig from the start > run box. click on the startup tab and uncheck everything that really doesn't need to load and lines without a path or description. Reboot the machine, click the check box on the pop-up window and hit OK. You would be surprised and the kind of junk that legitimate programs try to load.