Does running 2 antivirus programs harm the computer?

I have AVG %26 AntiVir Guard and both run cocurrently. I've never had any issues with either of them but I wondered if others believe it to be harmful.

And please refrain from posting about McAffee %26 Symantec/Norton, I have no faith at all in their programs.

Does running 2 antivirus programs harm the computer?antivirus programs

Not that I've seen. Not on mine. I guess it depends.

Does running 2 antivirus programs harm the computer?computer protection

Ya it reduces your system over all efficiency and makes it slow as both of them run at the background.
Well in the past when I tried running two at once I couldn't access my computer.I don't know about harm,but it was a headache.
Combining some of the answers posted, if you have a real-time monitoring enabled for both, it would probably put undue strain on your system resources and could lead to a system crash depending on how much memory you have/what else your computer is running. It doesn't hurt to have multiple programs installed if you schedule periodic scans and use one for real time monitoring. There are some really good AV programs out there that shouldn't require you to have more than one such as AVG.
They are going to make your PC crash. Get rid of one of them.
You shouldn't run 2 antivirus programs at the same time. It can severely slow down your computer. They both try to scan the same file at the same time and they end up conflicting with each other.
They say that you should only run one because they might conflict with each other or slow down your puter. It is Ok to run all the anti-spyware programs you want tho. Same with firewalls, only run one software firewall at a time.
It will not "harm" the computer, but if the two programs try to scan the same file at the same time (and both as always scanning in the background) it will slow the computer to a crawl and could cause it to hang or crash.