When reviewing the number of available user licenses, the system shows an incorrect number.
Verify that the unlock codes have been entered correctly through System Configuration.
Verify with Sage that they have issued codes for the correct number of registered users.
If the above two suggestions don't work,
Navigate to your \mas90\home folder (Use file - run - *info to see where your MAS90 program is loaded if you don't know).
Within that folder, double click PVXWINACTV.EXE
If that doesn't work...
Within that folder, doubleclick $ACTVPVX.BAT