It does seem like a heat thing aka Thermal junction aka Tj max or shut off like any electrical thing that when it overheats it turns or cuts itself off. If you have a program that shows the temperatures like Speccy or SpeedFan that would at least see if that is the issue, if not temps then check Event Viewer then go to drop dwn Custom Views then the drop dwn Adminstrative Events. If of course you have time, seems like if it dies after 5 min you don't have too much time to check anything really. Never run a laptop on a couch or bed or anything cloth or 'fluffy' it needs to be on a hard surface and if you wanna curl up with it in bed (like most women I know) getta tray or coffee table book and put it on that....you need air circulation. The air vents could be clogged too, blow out the vents with compressed air or if you have a vaccuum cleaner turn it around (if possible) to where it blows rather than suck (kinda like my ex) I have a shop vac that works great for that with a tapered nozzle, instead of buying compressed air cans, one of the biggest rip offs in computing IMHO.