[Discuss] su stopped working

[Murray Strome]

I tried to su and got a message something like

su: cannot set groups: Operation not permitted

Doing some searching with Google, I found that my problem was likely 
that the the permissions were not correct for /bin/su  -- I think they 
were something like

-rwxr-xr-x

One of the items I found said that the permissions SHOULD be

-rwsr-xr-x    -- or 4755

Of course, I couldn't do anything from my user session, so I logged out 
then logged in as root, then did a chmod.

It now seems to work, but I am wondering how it got changed in the first 
place, and what other permissions may be incorrect.

Any ideas as to what I should be looking for?

Thanks.

Murray