[ILUG] problem using su to root

[Wynne, Conor]

What if you enter single user mode?

i.e.: at the lilo prompt, type: linux single

CW

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I am running Redhat 6.2. I am unable to su to root. When I issue the su
command I am prompted for the root password which I enter. No error message
is given, but I am still logged in as myself. When this began happening I
had a shell open as root and so was able to check /log/messages. This
contained a line indicating that I had logged on as root and then
immediately the session was ended.
Prior to this happening I made a failed attempt to install the public domain
korn shell (corrupt download).

Does anyone have any ideas about how I can fix this? Bearing in mind that I
can't log in as root.