General :: Lost Groups Within Network Environment

I am a member of five groups within our network environment, but sometime, one of our systems can only find the primary group I belong to resulting in, that I cannot use the tools I have put behind a specific group. Sometimes it gives:

Code:
$ groups
meten1
instead of

Code:
$ groups
meten1 agilib cictest verigy tcntest
I think it has to do with the portmapper, since it is dead everytime it occurs.

Code:
$ /sbin/service portmap status
portmap dead but subsys locked
I checked the NIS settings and they are equal to the systems, on which I do not see this issue.