Recently i have received a compaq to fix for a friend's family and have solved a number of issues except one major one. Right after the COMPAQ logo is displayed upon turning the computer on, it would often return an error stating that "A disk read error has occured, Press CTRL+ALT+DEL" which obviously restarts the computer. From here, it will either decide to work and load windows normally or return the same error. I have also receieved the occasional "Error loading operating system". Sometimes it works, sometimes it does not and i have no idea what the problem is as i have installed a new HD and installed the OS on it and running the old HD as a slave. Im going to try removing the 2nd original HD to eliminate that potential problem but i dont believe that will solve it. Any ideas would be much appreciated. Thank you.

If this has happened with multiple drives, perhaps a new cable would help. Life is more painless for those who are brainless.

A flakey CD- or Zip-drive could possibly cause such errors. Try another cable (as suggested above) but also try disconnecting all other drives.

Also try chkdsk /r from the recovery console.