My Lenovo SL500 laptop won't start up! When I turn it on, it runs perfectly until right after the Microsoft loading screen, when a blue screen with an error message pops up for 1/2 a second and then the whole computer restarts! Please help!

Hit the f8 key several times while it is rebooting and go the screen that allows you boot to windows, boot to last know good confifguration, boot to safe mode, etc... screen. On this menu you will find a selection that will allow you to stop the blue screen on the error. The error will tell you what the problem is. However from previous experience I can tell you that more than likely you will have to reinstall Windows. If you haven't backed up your data and need to recover it, It might be a good idea to setup the disk as an external drive or secondary (slave) drive on another computer, copy your data to a flashdisk or other backup device, reinstall your hdd as master/primary drive, boot to cd and reinstall windows. Have fun, let me know how it goes.