strange kern.ngroups problems

[jonas]

Hi questions list,

I have a set of users in a NIS/YP database who may login on multiple machines. 

Now for some reason, on one of those machines (5.3-RELEASE-p6), any user who 
belongs to more groups than 4 on the NIS/YP server cannot login any more.
If I'm using su as root to become this user I get:
su: setusercontext: Invalid argument

This is only the case on this one 5.3-R-p6 machine. All machines have 
kern.ngroups set to 16.

While I'm certain I have not changed a lot from the default install, is there 
any place other than the kern.ngroups sysctl variable that I may have changed 
by accident to decrease the max groups per user?

I could also provide output from truss down to:
setgroups(0x11,0xbfbfe660)		ERR#22 'Invalid argument'

Thanks,

-- 
br.
j.