If safe mode runs okay but normal mode does not, it's usually caused by a bad 3rd party driver or an application which includes drivers (eg firewall, antivirus, CD/DVD software) which Windows installation does not get along with.
Most 3rd party drivers are not loaded in safe mode, that's why safe mode is able to run okay.
If you can recall having installed something of that type just before the problem first occurred, uninstall it in safe mode then see if your PC will boot to normal Windows.