(updated February 1, 2010)
The PearPC control panel is used to set up PearPC. Without it, the emulator must be launched at the command prompt.
Consult the PearPC setup guide for tips.
Check at the E-Maculation forum for support.
The PearPC Control Panel is sort of flakey. I highly recommend creating your own configuration file using Guillaume Jamet's online config file generator and launching the emulator from the command prompt.