FMP 6 vs FMP 5.5 under 10.2 - code 1000 error

I've been running FMP 6.0v1 under OS 10.1.x and recently upgraded to 10.2. FMP 6 seems to run without problems. I had a need to open a database solution in FM Developer 5.5 (since there is no 6) in order to export a DDR file for analysis. Filemaker Developer 5.5 failed to launch with an "unexpected error occurred: code 1000" error. A copy of FMP 5.5 unlimited on this same machine fails with the same error.

After re-installing Developer, it opened correctly and I was able to export the DDR file. I then re-launched FMP 6, did some code fixes, closed 6 and tried to launch Developer 5.5. I now get the same "code 1000" error I got prior to the re-install. I'll re-install Developer 5.5 but it feels like 6 and 5.5 share a common, incompatible preferences file. Does anyone know if this is the case... and if there is a workaround? I'll update 6 to 6.0v2 but there's no reference to this problem in the release notes.