ScanReg Loop problem

I have an AMD Athlon processor desktop PC running WIN 98SE. Every time it booted a warning window opened stating the there was an error reading the system registry and scanreg runs and tells me the registry has been repaired. I reformatted & reinstalled windows & kept getting the same thing. So I replaced the hard drive. Installed windows, updated my drivers and the loop is back again. When I looked for a registry backup file in sysbackup folder the only cab is rgbad.cab. Someone posted this exact problem back in 11/00. As it turned out the problem was a defective Pentium Chip. Here’s my question: What is the easiest way to find out if the problem with my processor? Or perhaps with another piece of hardware? Is there a diagnostic program out there I can download that might tell me? Thanks!!!