>Since around 10 days I am not able to login to UT with my favorite FIreFox browser anymore. See attached screenprint. Anybody around to show me where / which setting I have to review to use FireFox again?

Thanks for having sent the image. Basically, the images are not being shown. If you look at that page, all images are being intercepted, not being shown or simply ignored. See if you have a setting for that turned OFF. Otherwise, your WiFi connection might be a factor.