I built a PC containing the following:

Main Components:
Microsoft Windows Vista Ultimate 64-bit OS
HP 2159m 21.5" LCD Monitor
Intel Core 2 Quad Q8300 2.5 GHz CPU
Arctic Cooling Freezer 7 Pro CPU Fan
Intel DP45SG Dual Channel 1600/1333MHz Mobo
Sapphire HDMI Radeon HD 4830 512 MB 256-bit GDDR3 Video Card
Apevia X-Dreamer II Mid Tower Case w/4 Case fans
Rosewill RX850-D-B 850W Power Supply
A-Data (2 x 2 GB, 2 x 1 GB) 6 GB RAM (total) DDR3 1333 MHz Dual Channel
Western Digital Caviar Black 640 GB 7200 RPM 3.0 GB/S HDD
Creative Sound Blaster Audigy SE 7.1 Channel
Edimax EW-7128G PCI Wireless Card

Extras:
Nippon Labs ICR-BB Card Reader
Samsung DVD Burner Black SATA Interface

For the last three weeks, I have been installing and uninstalling software and hardware, updating and downgrading BIOS, clearing CMOS, etc, trying to troubleshoot the problems I've been having.

My troubles boil down to this: the computer runs perfect, once at running temperature. However, when I try to start the PC from cool, it freezes EVERY time when cool.

A forum member from a Yahoo Groups forum told me that it sounds like a connection on my mobo is broken, and contracts and splits as the computer cools, then expands and the electrical connection is made again once at running temperature. He told me to start up the computer and let it run it BIOS until it gets to temperature, then let it boot. I did that, and it worked.

I'm wondering what any of you have to say about that.

I also notice that my clock is constantly needing to be set, possibly related? Thanks for the input.

The clock problem is cause by your bios battery being flat or the cmos jumper being in the wrong place. Check the cmos jumper in your mobo manual, if it's in the correct position then go and get a new CR2032 battery and fit that.

If the clock and the freezing have always coincided then it may just be that your bios is unable to store hardware information and a new battery could possibly cure the problem.

It's certainly worth a try.

Tried replacing the battery, no luck. Seeing as I've done every test I've been told to do, and can find no hardware problems, I sent the motherboard in for an RMA. I decided to get a different brand and model, since (from looking at the forums on Intel's website) there doesn't seem to be any end in sight to problems.

Thankyou cathi for those kind words. I do my best to help as many people as I can.

From this distance, I buy the dry joint or similar theory - the connexion expanding on heat up.

I installed my new motherboard two days ago. My problems are now completely gone.

Great. Do please mark this thread as SOLVED and good luck.