Reinstalled Windows 8 and the hard disk light has stopped flashing constantly and has returned to normal. However, now I have another problem. Windows won't install Windows 8.1, it downloads it, reaches the end of the installation and then comes up with a blue screen resulting in it restoring Windows 8 and giving an error code. It's done it three times now. I'm going to have to clean install Windows 8 again and go through the whole process, tried everything else I found from googleing. Hopefully, this will resolve the problem and I'll let you know what happens.