I have also had issues with random shutdowns, usually when I play a game. I am using a 2 year old Pavilion DV7 Notebook x64-based PC with Intel Core i7-2370QM CPU @ 2.20Ghz, 2201Mhz, 4 core(s), 8 logical processors that was only recently put into full time use. For the 1st year it was used ~5 times. Now that I'm using it as my main PC, I rarely use the battery, maintain the laptop on a hard, flat surface (hardly ever move it), use a cooling fan, and continue to experience random shutdowns. If it was an overheating issue I assume the system would not start right back up but mine always does. This happens approximately twice a day and is extremely annoying and inconvenient. I've always purchased HP products but will likely never purchase another notebook as I see this issue is a problem on most models and I see little in the way of fixes.
I haven't attempted the above fix yet but must say the instructions just seem wrong. If you remove the ac and the dc what is powering the device to allow a manual shutdown? I will attempt this but have major doubts. Will update after attempt.