Hello there, solved it for my purposes :-) but I haven't found a reason why it happened. Decription: I found out, that i forgot to clear the file /etc/default/useradd. Due to this the following line seemed to do make the problems in there: GROUPS=dialout,uucp,video,audio So users were added to these secondary groups as well. I removed this line and everything worked fine again. No file seems to be corrupt. After that to make it complete in removed all users accidently added to that groups - they shouldn't have been int these groups anyway - silly me. Still I wonder why that silly thing occured to me. Seems there ist some kind of limit for a line in /etc/group... or something else similar. the line of each group ind /etc/group was filled with approx. 400 users - just in case anyone wants to check IF theres really some kinda limit. I dont want to make any further tests...this was enough action for today :-) Anyway, thanks for allyour thoughts :-) Holger