Unfortunately the issue can't be fixed at the moment. The reason for that seems to be the recent updates that might have gone wrong. So please use the the IE ( I had to switch to the browser too ) or if your Firefox has the problem with posting only you can use the BB Code Editor instead of the Rich Text one. You may try to disable it permanently in your personal settings of the forum or you may use the small icon with the "wrench" at the top bar on right of the post window. But please remember that the kind of disabling is for the current posting window only. When you posted, the Rich Editor will be set as the default one again for the next post window. The displosable setting is better to make before you can start writing of your text or uploading images.