Ok removing the 'objects' folder did the trick also with me.
I have had installed the mat baker package, but it is uninstalled atm. However the updater shows it still, as being 'not installed', but still somehow it remembers.
I also installed the BF2editor.
I just started with the onject folder, and yes now it seems I can play all maps. Does this mean I cannot use BF editor to full potential anymore because the objects folder is now missing (I saved it for now somewhere else)?
Thanks a lot guys, I hope the problems stay away now