Laptop won't start windows

Hello,
I have a compaq laptop and when i turn it on it goes through the check and then comes up with the boot load then to a windows did not start successfully screen. it gives me the option to start or reset to last good point or enter safe mode. but anything i click on just brings me back to the same place. Does anyone know how i can get past this? I've tried the f8 key but that doesn't do anything and the f 12 doesn't either. Any help would be greatly appreciated. Thanks