just put together a new system with a msi p35 platnum with Q6600 GO, 2gbx2 ddr2800, msi 8800gt.

things worked well for about 2 hours, then the system crashed and would not power up. The standby led on the MB was illuminated. When I disconnected the cpu power supply the board started right up. I replugged the cpu power and nothing. I then took out the cpu with the power supply hooked up-->nothing. No cpu & no power-->board fired up.

Thinking I will return the MB. Has anyone ever experienced this?

What exactly do you mean by "started right up" and "board fired up"? Clearly, a board will not work properly without a CPU, so you'll have to give us many details of exactly what is happening. Also, what model power supply did you use?

To try to understand what your saying...

When you say it powers up, meaning the fans all turn on? (with out the 4/8 pin power for the CPU)

And so with it unplugged in, it doesn't do anything?

Take a good sniff on the PSU exhaust to see if something may have smelled burnt or have like an ozone smell.

It's really hard to say if it's the PSU / MB / or CPU at this point.

Since it ran for 2 hours, I would suspect the PSU first, then MB second. On the MB I'd look for any capacitors leaking or any bulges, unless its all solid state.

The MSI Platinum Board (same board as my neo2-FR) has a bank of LEDs on the front left hand corner what do they show?

The breakdown is in the manual of what they mean.