Once you start the PC on the BIOS/first screen to appear press and hold F8. Here choose "last know good configuration".
Still not working?
First we need some information, an OS and some basic hardware information and a clear description of what is happening when it freezes to start.
No matter how many different restore points I try, I just get a message saying "No changes have been made to your computer." How do I get it to restore? The reason I want it to restore is that it has taken to freezing so solid all I can do is switch it off.