I have been running diagnostics on a Dell computer that is freezing after about 10 minutes. Diagnostics show various SATA errors:
IDE device failed read portion of test; error code OFOO 75D
Error code OFOO 244 - message block 209914116 uncorrectable data error or media is write protected.
(1) go into device manager and see who made your disk (WD, Seagate, Hitachi, etc.). Download the HD diagnostic from the disk OEM. It will give you options. Usually there is a tab for SMART data -- this is the predictive fail, error counts etc. This is somewhat standard and somewhat vendor unique so it helps to use the right tool.
(2) HDTUNE PRO has the trial version. If you look harder on the same web page you can find the Freeware version that you can use forever.
(3) Windows has a good surface scan. When you scan it should reallocate bad sectors. Right click the hard drive, properties, tools. etc. Make sure you do the complete scan for errors, not jsut file system repair.
(4) CHECK your cables. Reseat each end.
(5) Try the PC with another disk and see if it stabilizes. Could also be bad memory, etc.
Its a bad time to be buying disks. (Thailand flooding = no disks = 3X price increases), otherwise I'd tell you that once a disk starts to go you are playing with fire. I wouldn't use a failing disk on a machine I wanted to have available. It's also a good time to double check your backup strategy. If the PC is a prebuilt, then make sure you created restore media (typically the PC asks you to burn DVDs and no one does). GL.