Your user screens may also be corrupt. Can you delete this user and their modified screens & reenter the user fresh & copy their screen sets from a user that doesn't have problems? Also, check that your users have full permissions in the registry to hkey local software macola, odbc, and pervasive on the local xp machine. The user should also be a local administrator of the workstation.
I'm with Andy, get off 102e. It was not the best 102 release. 102f & 100a are far better. I thought 7.6.200 & 200.5 were terrible (the first stab at switching to dll technology). 300c seems okay for those not using Peak Best OE previously. There are still some issues with integrating the Peak into vanilla Macola. A 166 error is pretty wierd.
If all else fails, there are some old btrieve gurus out there that might know the root cause of a 166 and I can send you in their direction. Post back and let me know.