Hello Jürgen, thanks alot for your help so far. The logs are attached to the reply. Something must have happened on Thursday, 31. July. The first time i recognized there was something wrong was on Friday, when i tried to start Firefox, and the failure warning showed up. I read the whole log files and found something that didn't match with what i did on thursday, i don't know what these files or services are. Take a look at the FRST.txt at "One Month Created Files and Folders", specifically at 2014-07-31 20:23. "Security System 2" and "Bupsystem", don't know what that is. Also the following entry at Addition.txt seems suspect to me: "Securita Scout (HKLM-x32\...\Securita Scout) (Version: - ) <==== ATTENTION" Thanks for your help and greetings from a german fellow. Ben FRST.txt Addition.txt