Why are you attempting to boot into SAFE MODE? If there is a problem in regular mode, then the problem is serious. You may have a defective hard drive or other hardware failure.
I'm trying to because i keep getting a message saying that my Windows XP isn't genuine and i need to reinstall XP home edition (according to a response from Microsoft) but i need to do it in safe mode.
Ignore it if you can... or use the Microsoft Genuine Check to affirm that it is good. Usually you can bypass that message, and it doesn't come back after Genuine Check.