Well, i added it and the first thing i've noticed is that my internet connection seem to be twice as fast as before. Don't know if it's just a presumption.

Now i have to wait and work a few hours until i know if it helped to solve the crash problems or not. Like i said, mostly it happens after a few hours.
By the way, the UUID error is still there.

21.02.08 11:19:04 firefox-bin[140] _CFGetHostUUIDString: unable to determine UUID for host. Error: 35
21.02.08 11:19:39 quicklookd[143] _CFGetHostUUIDString: unable to determine UUID for host. Error: 35
21.02.08 11:19:44 Console[145] _CFGetHostUUIDString: unable to determine UUID for host. Error: 35

=) Thanks so far!