Most of the time, the permissions error -61 is usually silently bypassed in the background and the program moves beyond it.
Make sure everyone is out of the program (if no one can get in, that part is easy) then launch it at the server. If it runs at the server and configures the system, packs the databases, and then opens with no errors try to then launch at one of the workstations.
If one of the workstations has the program locked open, try to get the program closed on that machine, by rebooting the workstation or server if necessary.
Double-check permissions on the Essential Forms Data folder. Users should have full control (read, write and modify permissions) on the data folder.
Check to see if the installed antivirus program may be scanning or tracking Essential Forms files.