I'm guessing this has something to do with your own custom files, the best thing to do would be to make a backup of your rl.dat and any custom and save files you have, then delete the save files (you can keep rl.dat there), and install the patch, then you should have no problems, and if you want to go back to the other save files, just uninstall the patch and use the old files.
The game itself has issues with editing teams that are in a saved competition (hence why you can't customise teams already in a save game) so the best option is to just not have any save games there.