PC Locking up

I have a problem with a Win 98 SE Pentium II 333 MHZ with 64MB locking up randomly. When it locks you have to power it off completly. CTRL ALT DEL does not work. I am thinking its a hardware problem based on the above. I have changed the RAM,Video Card and still no good, I even changed the slots they go in. Ran scan disk on the Hard drive (no errors found). I am wondering if anyone has ever had this same problem. I am thinking possibly the CPU or Mother board is flakeing out.

Any ideas other ideas or suggestions to try?