OS not found???

Computer: Compaq Presario 5000
OS: Windows 98
HD: C = original HD and D = newer HD

Problem: The computer froze so we restarted it and then a message stating that the computer could not find the operating system was put up on the screen and nothing else happened. We tried booting off a 98 boot disk and recover CD but that did not fix it. From the prompt (with boot disk) we tried to look at the HD's (dir) and first we could see the dir of C but not D and then A was the same as C and no other drives would read. Then we tried physically taking out the C drive and connecting the D drive as the C drive (we moved the jumper to master) and then a keyboard error occured on top of the OS not found.

Is it a virus? Is one of the HD going? Is the mobo going?

Hi Casper. First start by putting the system back that way it was before all this started happening. Then boot off the boot floppy (with no CD). Once at the A prompt type fdisk and press enter. Press Y then press enter. Then select option 4 to display the partition information. If it reports "no fixed disk present" check your cables (unplug them and reconnect them making sure you have a solid connection and retest. Next open the computer setup utility (BIOS) by pressing the F10 key as soon as you boot the computer and check to see if the BIOS 'sees' the hard drive. If there's an auto detect option, try it to see if the drive can be detected. Depending on your model there will be an IDE DPS Self Test:
Summary
This article demonstrates how to run the hard drive self test, that is available in the BIOS (Basic Input/Output System) of most newer Presario models, such as the 5BW130, 5BW220, 5WV294, 5007CL, 5106CA, and 5320US.
Introduction
The IDE (Integrated Drive Electronics) DPS (Data Protection System) Self Test will help in troubleshooting and diagnosing hard drive failures and error messages such as: "Error 1720 Imminent Hard Drive Failure" during the POST (Power On Self Test), SCANDISK running on every restart, bad sectors or clusters, "Non-System disk" errors, "Operating System Not Found" errors, and others.
Any system that ships with SMART III Ultra ATA/100 Hard Drives will have the Drive Protection System (DPS) that is accessible through the BIOS. The SMART III Ultra ATA Integrity Monitoring system is the latest incarnation of SMART (Self-Monitoring, Analysis and Reporting Technology) which provides for testing of all data and all sectors using a method called Off-line Data Collection.
This article will show how to access the BIOS and how to start the IDE DPS Self Test.
Information
Follow the steps below to start the IDE DPS Self Test:
From a powered off state turn on the Computer by pressing the power button.
When you see the red Compaq Logo repeatedly tap on the F10 key on the top row of the keyboard. If you are presented with a "Save to CMOS and EXIT?" windows tap once on the ESC key once.
Press Enter to select "English"
Press the Right arrow key until the "Storage" tab is highlighted
Press the Down arrow key until "IDE DPS self test " is highlighted in black
Press Enter.
Highlight the primary drive at the "Select a Drive" prompt, and press F10 for yes.
Press F10 to start the test. It will take anywhere from 45 to 90 minutes to complete the test depending on the hard drive size.
If the hard drive passed the test, then the hard drive is Ok. If the drive fails the test, replace it according to the warranty agreement.
To exit the BIOS setup, press ESC
Press F10 to "Ignore changes and exit". The computer will restart
Self-Test Error Codes
Value Description
0 The previous self-test routine completed without error or no self-test has ever been run
1 The self-test routine was aborted by the host
2 The self-test routine was interrupted by the host with a hardware or software reset
3 A fatal error or unknown test error occurred while the device was executing its self-test routine and the device was unable to complete the self-test routine.
4 The previous self-test completed having a test element that failed and the test element that failed is not known
5 The previous self-test completed having the electrical element of the test failed
6 The previous self-test completed having the servo (and/or seek) test element of the test failed
7 Reserved
8-14 Reserved
15 Self-test routine in progress

Well...after alot of different things, we backed up the hard drive (C) and reformatted it. It seems to be ok but i don't think it likes any version of winamp. oh well...thanks