Settings messed up after crash

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http://askubuntu.com – After an abrupt shutdown many settings were messed up: #1 Firefox was a mess. Bookmarks were gone, and I couldn't even add new ones. I had to reset firefox from safe mode and install all my addons and configure everything. This was a pain but is now solved. #2 The background in the login screen shows the one I chose with Ubuntu Tweak for a second, and then it puts back the default one. I tried changing it again with Ubuntu Tweak but it's still happening. #3 All my shortcuts in the sidebar were replaced by the default ones. I re-added them manually, also a pain. So how can I solve 2? And i (HowTos)