I find it hard to believe there is a bug in /etc/group. It's an ascii file. If you were having a problem with it, you would have a problem with all ascii files.
1. These techs who told you it's a bug - UNIX techs?
2. When you wrote "I read the /etc/group", what do you use to 'read' it? An application, cat command, more, ...???
3. If you read /etc passwd (or some other ascii file) does it do the same type of thing (you see the first line, hit return, and see the rest of the file?
Found nothing on the following site for bugs with /etc/group.
pcunix.com