FCK editor and build–in gallery don’t work together

Hello,

Since I’ve installed the FCK WYSIWYG editor (v2.4.1) plug–in I can’t use the build–in possibility (“Add media—>Add an image”) to add pictures to my post anymore. In FF3 on OS X the thickbox throws an JS error once I click the “Insert into post” link:

uncaught exception: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE)
[...]
[Break on this error] if($.browser.safari){//safari needs...p because it will not fire iframe onload

and the overlayed box turns white (empty) but nothing else happens.
In Safari the thickbox still closes, but the image doesn’t get placed in the post, which makes me think, that the FCK editor doesn’t work well together with this possibility to add imagery.

I’d be very grateful for any hint how to resolve this problem or how else I could my images from the media gallery into my post.

Thanks,
—trice