Rich Text Editor disabled after installing Organic Groups

I have just installed Organic Groups, and the option to edit content using the Rich Text Editor seems to have been disabled. I'm not sure if the two things are related, but I've never had any problems with FCKEditor before.

The plain text editor still appears, as does the code to exclude/include the element, so FCKEditor hasn't been disabled completely. I have checked to make sure and the user permissions are as they should be, so there shouldn't be any problems there.

Does anyone know if this is to do with Organic Groups and if there is anything I can do to fix it? I'm completely new to Organic Groups and pretty inexperienced with Drupal anyway so there's a chance I've missed something quite obvious!

Any help or advice would be much appreciated, thank you!