You may try to restore your PC back to defaults.
The process of restoring PC to defaults is simple, just hold the [alt] key and press the F10 key right when you turn the PC on to start the recovery program.
Check out all the new software that you have installed on your computer, if the software are not genuine and authenticated, remove them, because they may be the cause of problem.
Another way is, get in the BIOS and turn of the option of Autostart at system failure.http://supportforacer.iyogi.com/aspire/blue-screen.html
Hope this information helps you.