How does one know when the M1530 is having card issues?

I've read lots of posts here about faulty cards in the M1530 and so far I've seemingly been lucky enough to avoid any major problems with mine, but now I have some unusual behavior and I'm not sure if it's because of the faulty Nvidia issue or something more minor. Everything works normally, temps remain in the 70s on the GPU, but when gaming after a while on my external monitor linked with a VGA cable the screen will suddenly go black, then the image will come back a few seconds later with some stuttering, and then the game will resume but with a much choppier look. When I exit and go to the desktop the little taskbar notification says that the video driver has stopped responding and recovered. The only way to get everything running smoothly again is to reinstall the video drivers. I've tried many, many different drivers and this still keeps occurring, including both the latest from the official Nvidia website for the 8600M GT and the latest from the dell support website for my specific laptop. Strangely, this problem doesn't seem to happen when I'm playing on my laptop's screen, only the external monitor, but I might just not have noticed that, and in any case that still shouldn't be occurring. Do I need to get Dell to replace my motherboard like so many others on here, or is it perhaps something that can be corrected by some drivers I haven't yet tried? BTW, I also undervolt my CPU and overclock my card, but disabling both of these things hasn't stopped the problem from occurring.

 

I play a few games on my M1530 (COD4, L4D, World of Goo) and find that the only way to avoid video driver crashes is to play these games directly after a reboot WITHOUT starting any other applications. I'm running 186.81 on Windows XP 32 bit, BTW.