Here's what's bin happening
When I log into the computer, whenever I try to go into something like my computer or recycle bin or whatever, everything except the desktop pic disapears for a second, then goes back to normal, and nothing happens, so I can't get into my computer or whatever unless I'm browsing through another way (like if I go browse files in media player to look for a song, it lets that access it)
This has happened before, and once when it happened, my dad found a hidden user account on the computer which he deleted.
I think this mite be related to whenever we leave the internet on when we aren't using the computer.
Anyone help? How do I fix it? We have zonealarm and avg free edition.
I just noticed that avg is scanning the computer.
When it shows scanning in progress, what does it mean when it says "change" under result/infection?

I was just about to suggest running Avg Free or Zone Alarm Security Suite. It could be a virus under they re-downloads from the internet every day or once or twice a week. Have you ever had problems with trojans as this can cause lots of problems. Also when you say change, which files did it change , did you save a log of things if it did find something wrong. Also don't run Zone alarm and Avg at the same time, always turn one off to run the other. If the problem gets worse or you find new viruses or new problems then I suggest ( only a suggestion ) Backing up all important files, Emails, Word documents etc and re-install windowns. Also if there were viruses connected to any system32 files this could have cause the problem if they got deleted or any other system files got deleted.

You could also try this, Do a disk clean of the computer and get rid of any unnecessary files not needed, then try to run defrag. Some program clitches can be cause by low memory or CPU maxed out.

We recently did a defrag... which one u suggest we keep on?

Are to trying to describe that the whole desktop goes blank, but then re-appears?
If this is the case, try doing a system restore, or uninstall any new software that may have caused the issue... because more than likely something is causing explorer.exe to refresh itself. (Usually refreshes after a registry change is made)

Good Luck!