I tried one more time (uninstall/reinstall) after writing the above and guess what, it worked!
I run up-to-date R6 and dictionaries and my workstation is W7/32-bit. I ran the latest version of WorkstationSetup.exe v6.17.1.250 without running it as an administrator. I chose "C:\Recorder 6 Workstation" as my install directory and NOT the default. Once installed I checked the Workstation setup using RecorderSystemCheck.exe and no errors were returned.
I have also (previously) had to give all users Full Control (effectively) of the Recorder 6 Server directory to run under W7. Previously with XP this wasn't needed.
I can now invoke my workstation, install maps and AddIns without error.
Rant over :-) Apologies...
Les Evans-Hill
Senior Data Officer
Butterfly Conservation, Butterflies for the New Millennium and National Moth Recording Scheme