It wont start up

Could be this is a driver error on boot up, when it starts to boot up keep pressing F8, this will bring up the safe mode menu, look for the line and highlight 'Last Known Good Configuration' and press Enter.

If this works all is well, but if not press F8 again o boot up but this time highlight the line 'Start Windows in Safe Mode'.

If the laptop then boots up in safe mode without shutting down, run your anti virus and spyware programmes.

If non found and the laptop still has'nt crashed, then it's a driver problem (as not all the drivers load up in safe mode) and you will need to try a system restore to before the problem started.