When adding a new user in userconf, if you do not assign that user a group (which is listed as optional), it creates a blank group entry in the group definitions each time.
Which then creates the added annoyance of causing an "Invalid parameter" error every time that user logs on.
See also #6245 and #6089
This was fixed in Linuxconf 1.16r7.
We will be making an errata release based on 1.16r10 or later, which should fix this bug. *** This bug has been marked as a duplicate of 6089 ***