First, I would stop the computer from rebooting by going to control panel, Performance and Maintenance, click on system, in the window that pops up, click the advanced tab, and under startup and recovery, click settings, in the window that pops up, under system failiure, untick the tick in the "Automatically restart" box.
Next time it bluescreens, tell me the error codes on the bottom lines of the blue screen, ALL OF THEM.