to stop it restarting and get a useful error displayed that may help find the problem click:
start/control panel/system/advanced/start up and recovery/settings
untick "automatically restart"
next time it crashes it will display an error,write it down.
in the meantime have a look in:
start/control panel/administrative tools/event viewer click on the system and application tabs and look for red x`s these are errors.click each error to get more information on them.may help.