I don't know if it works the same for Jaz drive, but it worked for my Zip.
Go to device manager and click  on disk drives, NOT on anything that refers
to the Jaz  or its controllers. If you see a reference to your Jaz drive
under disk drives,  double click on it, then the settings tab, where you
can set the first and last letters for your Jaz drive. (set them both the
same as you want the drive letter to be) Hope this works.
ed

At 11:51 PM 5/30/98 -0400, you wrote:
>Hi All,
>
>I have a partitioned harddrive; drive letters C:, D:, E:, F:, and G:.
>My CD-Rom is drive M:.  I have a last drive statement in the config.sys
>file that reads LASTDRIVE=R.
>
>The Jaz dive is external.  When I turn it on it assumes drive letter D:
>and reassigns the logical drive drive letters E: - H:.  When this
>happens my program files cannot be found.