Probably due to: 1. inproperly configured channel modes or 2. due to a certain script.
What to do to fix this:
1. Check the channel modes with '.chaninfo #channel' (replace #channel with the actual name) and check what it states at 'Protect modes (chanmode)' then change this (if needed) to suit your needs with '.chanset #channel +/modes'
2. Unload all your loaded scripts and find the one causing problems. Check #1 first.
Once the game is over, the king and the pawn go back in the same box.