Sometimes the computer will lockup, so it can only be used by a system administrator, but my husband and I are the only accounts on the computer and we are both administrators.  It asks for a passcode.  I usually just turn off the computer and turn it back on and its ok.  But it does it about once a week.

 

Then sometimes a windows error message comes on and says that my virtual memory is running low.  Same thing, I just turn off the computer and turn it back on and it is fine.

 

I have many small issues, but can't figure out what is causing them. 

I have McAfee virus protection as well as Adaware spy protection, so I don't think its a virus, but I've had these problems since I've had the computer??  Please help??