OK...we have an IBM Aptiva we bought around 98.  Here's whats been happening...

First sign of problems is when the screensaver locked up.  When we restarted the computer, our DVD ROM and Zip drive wouldn't show up.  My dad asked me to look at it, and I couldn't see anything wrong.  With in a day, a friend and I were going to play a game over our network, but when I looked at the computer, the screensaver had locked up again.  I restared it, and I got an error in the bios saying that my system proporties had changed(it was saying it didn't see any IDE devices on either controler...)  I cut it off, the back on, and it was fine.  Just last night, the DVD and Zip quit showing up, even after we shut it down...  The system proporties didn't show but the primary controler, and the bios showed the secondary controler was empty...  We've checked the cables, and they are fine.  It show no conflict between the controlers or anything else, but I cant really see the secondary controler any more.  The computer has not been changed hardware wise sence we got it(except the RAM we added about 1 year ago...)  So what could be the problem?