System Lagging Problem

[Bigvall]

System Specifications

Processor: 3200+ AMD 64 athlon
Memory: 1024MB
Chaintech Motherboard
Pioneer DVD burner
Operating System: Windows XP Pro

That should be sufficient for information. I had built a new computer myself this last Christmas and everything was working fine. Sometime in April I started to get Beep codes for errors in accessing my RAM. I then brought my computer home from school and a new problem came about. My computer started to lag behind randomly. It didn't matter what I was doing, I could not have any programs running and it would go to 100% CPU usage and lag for about 15 sec, then catch up and repeat this process 5 to 8 times. The machine would then go back to normal again. This lagging sometimes only happens once before it goes back to normal operation again. In the in the administrative tools for Windows XP under system error records, I was getting an event error 11 with a source of cdrom. The description was a bad IDE cable. I bought a new IDE cable and replaced the one for the cdrom. Still didn't work, unplugged my cdrom completely, still didn't work. replaced the IDE cable for my hard drive, still didn't work. I then was given a brand new motherboard and the problem still continued. I no longer got the beep codes for my RAM, had determined it was a bad motherboard. I have been told the only other thing that could be wrong is my processor is bad. I would like to know what everyone thinks.