Unfortunately, the object block variable error is the second most common catch-all error (well, it could be the first or the third most common) so the cause could be most anything.
You have not mention if you tried re-installing the FRx client on this workstation or not but you should try that. You should also, since this is SP12, try running the FRxreg67.cmd file from the workstation. that file is located in the FRx folder on the server. It must be run as a user with local admin rights so you should probably right click it and select run as administrator.
Here is one more thing to look at. On the server, in the FRx folder, open the FRx32.cfg file with NotePad and look at the line for Directory. This indicates where FRx was installed. If that is a mapped drive, make sure that the workstation has that same drive letter mapped as does functional workstations.