I have a 3 year old sony vaio that i wanted to upgrade from Vista to Windows 7. I installed Win 7 and because it was dusty i decided to open up the laptop and dust it off with a hair dryer(cold). When I started the computer, after 2 or 3 minutes it turned off unexpectedly. I restarted it, and while Windows was loading it shut down again. It did this a couple of times and now it seems it's OK for the last 15 minutes no shut down.
Do you have any idea what can be causing the problem? Is it software or hardware? The laptop seems to be working perfectly now, and all components seem OK.