I have been having a problem on my Dell Precision M6400, where Windows 7 was starting to lockup, not where the mouse would stop working but enough of a lockup that any application I could click on was rendered useless with the spinning orb. I ran antivirus scan, a spyware scan, a malware scan, cleaned out my hard drives, defragged the HD, performed a sfc /scannow, even checked my hijackthis, and nothing stood out. This lockup would happen anywhere from 15 minutes to 2-3 hours after a boot, and was getting very hard to find. I went back to another problem I had early on with this laptop, heat, I fired up speedfan, which can be acquired here http://www.almico.com/speedfan.php for free, the temperatures looked weird but not out of the ordinary, or so I thought. That’s when I started to run out of ideas, but I did think it seems to happen when I am looking at something a bit more taxing on my graphics card, so I went to nvidia’s site and grabbed the video drivers for my quadra 2700 FX card, installed them, rebooted and looked at the temperatures again, the GPU temperature dropped almost 20 degrees Celsius and changed the ambient temperature quite a bit as well, and the laptop has been running for 10 or so hours now with no issues of locking up.
Just wanted to throw this out for anyone else that may have troubles.