If your computer is freezing on memtest, "like it usually does" ... this is the cause, and untill you fix that you wont get anywhere.
Flashing the bios wont solve it. You are overclocked or not? If so, go back to standard, and see if that will get you through memtest. Chances are if you have failing memory your computer is saving you the hassle of a malfunctioning Operating System. Once you can pass Memtest for a good hour or so try running a new Operating System install. It should run.
If your mem is faulty it cant run an installation process.