Frequent BSODs on Win 7 64 bit, 'bad pool header'

Okay I will start driver verifier now and let you know the results :)

Just to give you a quick update, I've had driver verifier on and left a game downloading on Steam while I grabbed some food. When I came back to it a couple of hours later the computer was completely frozen and unresponsive, but hadn't actually BSOD'd so I have no DMP file to upload. Interestingly though I've had it BSOD a couple of times when I've been downloading stuff on Steam in the past, and it erased all the progress of my download. However, after restarting this time the download resumed from where it stopped at the freeze, so that's a bonus at least!

Hello again Arc. Just had a very strange crash. Turned my computer on after coming back from work with driver verifier still running, and it wouldn't get past the 'Starting Windows' screen. Tried a few restarts and let the system repair try to fix the problem, but nothing happened, couldn't even launch in safe mode as it wasn't getting past that screen. Thought I'd try removing the 2 USB devices in there (a USB stick and a USB bluetooth dongle) and that made it work fine! Could driver verifier have been causing one of those to stop Windows from launching, might that suggest there is a problem with one? I had them both in yesterday when it was working fine which seems odd. Ah the confusion of computers :)

It seems you may be right, just now before disabling driver verifier I plugged the bluetooth dongle back in to test and my system froze straight away! No BSOD but it was completely unresponsive and I had to do a hard reset. How strange, I'd previously been using the bluetooth dongle for months with no problems at all. Maybe a new driver conflicting with it?

I will disable verifier now. I don't know if a dump file has been created because it didn't actually BSOD, but please find attached my latest SF diagnostic file.

Yep I will see how it goes without the bluetooth dongle, I only use it to connect my PS3 controller wirelessly to my PC, which I can do through the USB cable anyway so shouldn't need it. By the way slightly off topic but love your signature, I've always been a big Final Fantasy fan

Well that didn't last long! Just had another BSOD and the bluetooth dongle is not plugged in. Please find attached the SF diagnostic file with the most recent crash dump in it.