Unfortunately "freeze on startup" can be caused by a lot of different things.
It could also be hanging when it tries to detect the hard drive(s), or your RAM may be going south, or it could be something else entirely (motherboard or PSU).
Temporarily disconnecting the hard drives will tell you whether it is a hard drive related hang. If you can get it to boot from a CD, you can run Memtest86+
to check the RAM.