That advice no longer applies to Paragon Chat 1.0. It was redesigned specifically so you don't have to worry about UAC, running as administrator, and whether or not Windows is silently redirecting files written to the COH game folder. It puts its own files in your user profile where you don't need any special permissions, and it only ever reads data from the COH folder, never writes.
The best thing to do for the 'critical files cannot be found' error is to delete the ParagonChat registry key under HKEY_CURRENT_USER\Software. If you aren't comfortable with regedit, you can also try modifying the shortcut to add -nux to the end of the command line (after the .exe, and make sure there is a space).
Future versions of Paragon Chat will handle this better and give you a way to find your COH folder again if the one that was initially used got moved or deleted.