Source:  LOGOUT.EXE

Explanation:  LOGOUT thought a certain drive was valid, and DOS could not set the default drive to that letter.

Possible Cause:  When LOGOUT logs the user out of the default server, it leaves the user attached, but not logged in to the server. LOGOUT tries to leave the user mapped to a valid network or local drive. LOGOUT tries to find the first valid drive. If a valid drive is not found, the error message No valid drives are available to assign default to. is returned. If a valid drive is found, LOGOUT calls DOS to set the default drive to that drive letter. If DOS cannot locate the drive that LOGOUT thought was valid, or cannot set the drive to the proper letter, this message will be returned to the workstation.

Action:  Try issuing the MAP command to see if any drives are available; then change to that drive with the drive letter: command. If these attempts fail and the user cannot find the LOGIN.EXE or MAP.EXE program, reboot and allow the shell to connect the workstation to a server that contains LOGIN.EXE or MAP.EXE.