Gigabyte GA-8SIMLP mobo + p4 2.6ghz 400 FSB SL6PP = cpu hang

[pinkj]

Hi and thanks for reading!

I've recently upgraded my processor from a pentium 4 2.0Ghz Northwood with a 400 FSB to a pentium 4 2.6Ghz Northwood with a 400 FSB. according the Gigabyte CPU compatibility list, this should be the fastest processor possible for the GA-8SIMLP mobo.

However, once i had it installed, my computer keeps freezing. it usually does it 5 to 10 minutes after Windows XP or Ubuntu 7.10 loads completely.

Out of curiosity, I played with overclocking it in between 2.7 and 2.8Ghz and I've randomly been successful to have the computer run for more than an hour. but this is rare. I don't think I have overheating problems as I have my CPU monitor warn me when the CPU reaches over 60C and I've had my 2.0Ghz processor pass that mark many times in the past without my computer hanging.

I'm running out of ideas and I really dread the idea of going back to my 2.0Ghz processor. Does anyone else have ideas?

Thanks

edit: i have upgraded my BIOS to the latest version (F6) and i have applied, as per the instructions, Arctic Silver thermal grease. but the my cpu was hanging before i applied the thermal grease.