Group Wiki Plugin Fails to Save

Sorry, I realise this is not a WPMU plugin, but I was just wondering if anyone had come across this issue. Whenever I try to save a wiki page, I get re-directed to an error page. I've really got no idea how to approach this. I am working at a school and wiki functionality is key for teachers, if I could get this working, I'm sure I'd get them all on board. Any suggestions would be a great help.