OK, I burned the ESTOOL program onto a CD, then booted from that CD at start up. I ran the full diagnostic. When the test finished, I was told that an error had been found and that I should run ERASE HDD, after making a back up of everything. I had already made backups of all the data I wanted to save, so I ran ERASE HDD.
When that completed, I restarted the computer and went to the boot menu. 3 options appeared:
SM-HL-DT-STDVDRRW GSA-H2OL (I belive this is the CD in the CD drive)
3M-SAMSUNG SP2504C (I think this boots from the main hard drive, like usual)
Ut165 USB2FlashStorage 0.00
When I tried the first 2 options with the ESTOOL CD still in the computer, lots of lines of text went past really quickly and then I was taken to the ESTOOL program.
I took the CD out and tried the first 2 options again. They both took me to a blank screen with just a few lines of text:
Disk error
Press any key to restart
(After pressing a key)
Reboot and Select proper Boot device
or Insert Boot Media in
selected Boot device and
press a key_
I thought ERASE HDD would only delete files and programs, but I think it's removed Windows as well. Is there any way I can get it back?