Given you are unable to load other C3PO’s, I suspect you have a faulty GroupWise client installation.
I have seen one other instance where a mismatch of GroupWise client files would stop any C3PO from loading. This was bought about by a fault Zen-based client installation. The problem was solved by uninstalling GroupWise, then re-installing from a CD.
I would suggest you uninstall your GroupWise client, check all files are gone, then re-install from a CD or software distribution directory known to be sound.
I hope this helps,