Can't fix I/O error and can't run recovery console

I am getting an I/O error while trying to do a DriveImage backup. However,
I am unable to run ScanDisk/CheckDisk. I schedule it to run right after the
next boot but it seems to fail immediately. When I try to boot into the
recovery console to run it manually I get a request for the Admin password
which prevents me from running that.

This is a replacement boot drive -- I could never run CheckDisk on the
previous one either.

Can anyone help me solve this problem? Is there any other software that
someone could recommend to enable me to mark the bad sectors on the drive?

Thanks.

Tony Zackin