This is not a question, this a description of how I solved the above problem in my case. I searched the web extensively, and only found the eventual solution by chance while messing around on my own. This is included for the benefit of those that follow. This was for Windows 7 on my Qosmio Toshiba.
- Computer shuts off randomly, but especially while browsing, and esp. during video games, or playing videos.
- Computer will not restart after shutting off, until being completely unplugged (if necessary even from the battery).
1. My computer shuts off randomly (and or shuts off while the battery is still in).
> I have ruled out the PSU as a problem
> I have ruled out overheating
> I have ruled out the CPU
+ Seriously consider the possibility that the problem is software related.
I refused to believe that this problem was software related because it made no sense to me that it could be. I disassembled my computer and looked at everything, and nothing was wrong. As for as I could tell the bios was all working. I knew the problem was not PSU related (the power cuts) because they would happen even if the battery was in. I knew the problem was not heat related because my computer could withstand a stress test and would not turn off. Finally windows started locking up and I was convinced that the cpu or motherboard must be failing. No.
When I went on my ubuntu (linux) side after my windows had pretty much died, I was shocked to find that everything worked perfectly. No lock up,not power cuts, no nothing. This is how I realized that my problem was actually software related. Therefore seriously consider the possibility if something similar is happening to you. Obviously some questions still go unanswered. For example why could the computer not reboot after a random shut off, unless it was completely disconnected? I still don't know, but this much should get you up and running in the meantime.
I will post some useful diagnostic links later.