Deleting PC Setup Preferences is know to fix avariety of ills. Here is the latest example, taken from the March 5 Info Alley:
"After installing Mac OS 7.6 and PC Compatibility 1.5 software, everything was working fine. However, after installing Open Transport PPP 1.0 and restarting my computer, I get this error message, "Sorry, a System Error Occurred. PC Setup, Unimplemented Trap." What is wrong?
During the installation process, the PC Setup preferences file was corrupted. To resolve this, you need to throw the PC Setup preferences file in the Trash, empty it, and restart your computer. A new PC Setup preferences file will be created with default settings."