su - problem

[Vu N Nguyen]

Hi all,

Recently, when I try to 'su', I have this kinda problem.
---------
$ su
Password:
Error sending status request (Operation not permitted)
Error sending status request (Operation not permitted)
Error sending status request (Operation not permitted)
Error sending status request (Operation not permitted)
su: cannot set groups
Error sending status request (Operation not permitted)
---------

Could someone explain and/or give me a solution for this issue?

Thanks in advance.

Vu Nguyen