Windows 7 Crashes to MB flash screen - Mouse lag upon reboot

Hey all,
New to the forums... I was told to join because there's a lot of smart folk here. :)

I'm really at a loss here. I recently gave my GF my old machine and we've had nothing but problems. First, she started getting the hyper transport sync flood error which is due mostly to an issue with the speeds on the motherboard bridges. I tried rectifying that with various solutions like changes voltages on the bridge etc. It continued to happen.

So what I decided to do a few days ago is replace the MB with a new one. I went to Micro Center and purchased a micro ATX board, which is all she really needs. The only components on the board is my old GeForce GTX 460 1GB, and 8 gigs of memory (4 gigs each). She's using onboard sound, and we're using one hard drive and one CD drive. So, pretty basic setup.

A few days ago, I formatted the drive and re-installed Windows 7. The thing was running fine all week with the new board, but this morning she started running into issues again. The thing would re-start on it's own. She said it crashed and hit the MB flash screen. However, it didn't state that she received an error. When she got back into Windows, the mouse shape had changed to an odd, fuzzy arrow and the machine lagged every few seconds while trying to move the mouse around.

This also happened before. The only other difference is that we only have one system fan in addition to the CPU fan. However, I do have the side off the case at the moment. We need to re-visit Micro Center to pick up two more 3-pin to molex adapters, because there is only one fan connector on this micro ATX and the fans have the 3-pin connectors.

So, it COULD potentially be an over-heating issue, but this is exactly what was happening before when all fans were working.

I'm pretty knowledgeable with builds and troubleshooting, but am not really knowledgeable with reading Windows Event Logs or dump logs. I'll typically swap parts out until it doesn't happen anymore. I know it's not the best way of troubleshooting, but it always worked in the past until now.

We downloaded HWMonitor to view temperatures of the CPU. They range from 40c to 60c--way within acceptable ranges. So, not sure there.

Does anyone have ANY idea what this could be? Thanks!