Error 91 Disk Manager has been detected on drive, but Disk Manager is not running. If you are booting from a floppy, remove the floppy disk and reboot. Press and hold the <SPACE BAR> key as your computer restarts. When prompted insert your boot floppy and continue booting.

If Disk Manager is not needed, you can remove its signature from the Master Boot Record using the following command:
 
FDISK /CMBR <drive number>
 
where <drive number> indicates the drive where the Disk Manager signature is located (for example, 1).
 
 
If you are not sure whether Disk Manager is required, backup head 0 using the WRPROG utility. The correct syntax is:
 
WRPROG /bak head0.dat
 
The head0.dat file can later be edited, if necessary.
 
If Disk Manager is on a drive other than the primary master hard drive, you must change jumpers to make it the primary master. This is necessary because WRPROG will only access the first hard drive.

If Disk Manager is not needed, you can remove its signature from the Master Boot Record using the following command:  
 
FDISK /CMBR <drive number>  
 
where <drive number> indicates the drive where the Disk Manager signature is located (for example, 1).