Could it be a stuck or bad key on your keyboard?
[SIZE=7][SIZE=7][SIZE=14]I run xp pro sp2 and get a beeping sound from the tower every so often,with or without sound on.This happened when I downloaded yahoo games.I've since cleaned comp.(defrag,adware.trojans,etc) and removed them and the games.Still it didnt help.The beep is he same beep you hear when booted up and you too slow for password and it beeps to remind you.
It could be the antivirus with the option of internal speaker beeping when something bad is intercepted or it could be an overheating alarm
I can suggest you that you should go to check sound and software whether it works properly or not? I don't think it would happen like this. Eventhough it got hit my virus, it also have to show something alert you. Am I right? If possible, you can remove and reinstall your sound again.
the first thing i would do is go to bios and check the system temp, if its up round 50-60'c this might be the cause of the problem the other thing i would then think about is what you are doing when the system beeps, oh and like they said above double check that all the keys on the key board are not stuck and if you can try a diffrent key board, one other thing i would try is looking in admin tools and looking at the event veiwer to see if anything is recored in there (if you have trouble finding a entry in event veiwer wait till you hear the beep next and note the tiem and go lookin it up in the event veiwer) thats all i can think of now, but i would like to know if the beep does any thing else to your system other than just beeping.