Locking up!!

I have a older computer (233MHz) and I am having problems with it locking up–dead lock(CTL+ATL+DEL) does not help. I recently added a new hard drive and CD-ROM. I had some of these problems before I added these two things. Now I try to play games and they don’t work(Age of Empires doesn’t even have video, my son’s preschool game locks up after playing for a few minutes). I was told that some 233’s had too small of fans for the processor, so I clean out the parts with compressed air(Processor fan, power supply, motherboard) almost daily and they still don’t work. Any advice would be VERY much appreciated. Thank You all in advance!