What capacity and model number are reported for the drive in BIOS?
What does SpinRite think the capacity is?
Have you installed the drive's Alternate Capacity jumper? If so, then this limits the capacity to 32GB.
Could we see the partition table and boot sector with Microsoft's Sector Inspector?
http://www.users.on.net/~fzabkar/SecInspect.zip
Extract the above archive to the one folder and execute the SIrun.bat file. The procedure will generate a report file named SIout.txt.
BTW, I agree with tokencode. That is, clone your drive sector-by-sector ASAP, and then work on the clone.
BTW, if your drive has bad media or weak heads, then SpinRite will potentially accelerate the drive's failure. This is because it keeps hammering away at bad sectors until it succeeds in reading them, or until it exhausts the number of retries (1000 ???).