I found the solution. While checking the diagnostics file I attached I found that the local time on the hard drives was shown as "Fri May 23 02:49:09 2014 CEST" which is clearly not today. Then I checked the Date and time and found the very same date shown. Then I checked the BIOS and found that my settings were gone and back to default. Long story short: The CMOS battery on the motherboard just died and upon reboot today everything was messed up.
Changed the CMOS battery, set the date and time to the current and voila, community application work again.
Sorry for having you bothered and please excuse if anyone already digged deep into the diagnostics.
