User deleted from user groups

[bogdinator]

Hello ISPConfig mates,
I encountered some kind of bizarre behaviour on my server: some users form (let's say) webX use cvs on the same server. I've created a user group cvsusers and added all users created with ISPConfig to this user group with YAST (SUSE 9.3) The weird thing is that every time I create a new user or change some properties of the existing user through ISPConfig web page all the users I've added to cvsusers group are kicked out of this group and I have to add them again.
Is it normal? Can I do something to prevent this behaviour?

Thanks in advance!

[falko]

I'm not quite sure right now. Can you post /etc/group here?

[bogdinator]

Hi falko, here is /etc/group

root:x:0:
bin:x:1:daemon
daemon:x:2:
sys:x:3:
tty:x:5:
disk:x:6:
lp:x:7:
www:x:8:
kmem:x:9:
wheel:x:10:
mail:x:12:
news:x:13:
uucp:x:14:
shadow:x:15:
dialout:x:16:buser,cvs,web6_anonftp
audio:x:17:
floppy:x:19:
cdrom:x:20:
console:x:21:
utmp:x:22:
at:!:25:
public:x:32:
video:x:33:buser,cvs,web6_anonftp
games:x:40:
xok:x:41:
trusted:x:42:
modem:x:43:
named:!:44:
ftp:x:49:
postfix:!:51:
maildrop:!:59:
man:x:62:
sshd:!:65:
ntadmin:!:71:
messagebus:!:101:
haldaemon:!:102:
mysql:!:103:
vscan:!:104:
nobody:x:65533:
nogroup:x:65534:nobody
users:x:100:user1,user2....., userXX
cvsuser:x:1000:user1, user5, user7
admispconfig:x:1001:admispconfig
web6:x:10006:admispconfig,user1
web6_anonftp:!:12006: