Most of the articles about that event point to it being a 'driver' issue although there is no obvious culprit in each case. However, I presume that you have already checked for driver conflicts or out of date drivers that are having trouble with windows 7, and I also presume you have unplugged unnecessary external hardware to see if there is any improvement, so you can rule those out.
You might want to try and connect what you are doing at the time, with the time of the event to see if it is a specific software issue and is this happening with a desktop or laptop/notebook?