What is the release date for OrderEntry 81C.  The current service pack is (100507).  It should be installed.
If you still get an error, I will need to know:
Which version of Windows is on this station? 
Do you have CustomRP or ModRP directories under Softrak\OEWIN on F:?
If the station is a Vista or Windows 7 station, turn off UAC and try again.
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Regards,
Softrak Tech Support