Ulf reported a while ago that he was having difficulty deleting things from his courses. It would appear that Safari has no problem doing this, but Firefox resolutely refuses. I have recreated the problem on my Linux machine and a Windows box. It is possible that an update will fix this as many bugs are fixed in the new version. Currently, we use Moodle 1.7+ (2006101008) and the latest version is 1.8.2+. I will download and test the new version and do a test update on a local install. If everything goes well I'll do the update on the server.