The problem is that Vista User Account Control stops the workstation install from writing to certain folders used by the XP version.  Version 6.17 fixes this, but the workstationsetup.exe on your server is the one you had installed originally, which isn't upgraded, because the versions are specific to the install they are included with.   The full solution would be to make sure you have upgraded to 6.17, then unistall Recorder 6, then reinstall version 6.17.  Remembering to back up the database and all the users and map files  first. 

This isn't something to be undertaken if it can be avoided and what appears to have worked elsewhere is to replace the workstation install files on the server with those from 6.17. The three files required can be found at

www.Recorder6.Info/WorkStationUpgradeExperimental.zip

The three files should be used to replace those in the Recorder 6 folder. Make sure though that the original files are backed up  so that they can be restored if required.  The workstation installation should then be run in the normal way.