There can be allot of different things doing this, I would check your RAM first to make sure it is seated right.. Next Power supply, and The hard drive could be going bad.
Also check the Video connection.. Can you give us some specks of your computer ?
I have P4 2.4 GHz i845GL chipset HIS mobo, with 1 512MB and 1 256 MB RAM chips samsung 80GB HDD.
I have tried different RAMs as well.
PC works pretty fine for hours while booting windows through HDD. So if it would have been RAM then it might somewhere would have stuck through HDD as well. isn’t it?
A corrupted software from the cd can cause freezing but since you mentioned that you cd is working fine in other pc, then we can eliminate that angle. It is most likely a BIOS issue. Do a USB firmware update. Your last resort is to reset the Bios settings.