A friend sent me, this: Firefox immediately fails on startup. I don't have any idea what was going on, but the solution was to delete ~/.mozilla . Of course i was not near to the machine, so I had to give instructions how to fix this over the remote. Next Problem: My friend got only basic skills. Solution: Made a screencast how to fix it and sent it over. If you also don't know what "delete ~/.mozilla" meens you can follow that instruction: Howto create screencast: https://wiki.ubuntu.com/ScreenCasts/ffmpeg