Disk Boot Failure

A computer was frozen so I turned it off and back on. The hard drive started making a churning sound and then the error message DISK BOOK FAILURE, PLEASE INSERT SYSTEM DISK AND PRESS ENTER was displayed. Inserting the system or startup disk does not get me to c: When I boot to A: and type c:, I get invalid drive specification. CMOS does detect the hard drive. I put a good drive in this computer and got the same error message. I put the good drive back in the computer where I got it from and it ran with no problems.

Can you tell me what the problem is and/or how to fix it?