Adding second disk drive causes computer cannot boot from original first drive

Hello,

I own a Dell Dimension 4550 equipped with a 60000 MB disk drive. OS is Windows XP SP3. THe computer BIOS is still the original copy as when the computer was shipped in early 2003.

I tried recently to add a second disk drive in the computer. Second drive was mounted in primary bay and original drive was moved to the secondary bay as advised by the user guide.

Both drives have Parallel ATA interface; jumper setting is Cable Select on both drives (I tried as well Master / Slave setting which did not solve the problem hereafter described); original drive's capacity is 60000MB; second drive's capacity is 160 GB.

Since the installation of the second drive, the computer is no longer able to boot from the master disk. Even when removing the new drive and restoring the original confirguration (only one drive 60000 MB) is the computer no longer able to boot.

The switch light on the front is solid green. The diagnostics lights on the back are solid green for lights A, B and C and yellow for light D. 

When switching the computer on, a beeping sound is heard after about 15 seconds; on the screen a message invites to go to the boot menu or the BIOS setting menu.

The contents of the boot disk was analyzed on another computer and is apparently not damaged.

When accessing the BIOS setup screen, it appears that the BIOS is able to read the capacity of the two drives because the correct drives' capcity is displayed on screen. However the drive setup submenu displays "unknown device" for each drive instead of the drives' actual reference.

I tried as well to remove the new disk from the computer, and to de-activate drive 1 in the BIOS. De-activation does work but the computer is still unable to boot and the diagnostics lights remain solid green for A, B and C and solid yellow for light D.

I assume that something wrong happened with the BIOS the first time I tried to boot the computer with the second drive installed.

However I do not know how to recover from this situation.

Can anybody help ?

Best regards,

RobertAlexisJ