Strange System Hang

["Adam Williams" <awilliam@xxxxxxxxxxxxx>]

Since upgrading my system to RedHat 5.1 I have had the following condition
occured four times (in about a week).

I am unanable to login in as root or su to root.  I am prompted for the
password,  and upon entering the password and pressing enter,  nothing happens,
 the cursor goes to the next line and just sits.  If I hit control-C I go back
to my command prompt as myself.  I cannot switch to root on the console, in an
xterm,  or in a telnet.  And if I am already root in another window I cannot
shutdown or reboot,  the system accepts the commands and returns the command
prompt.  You see the wall message, but beyond that nothing happens.  In order
to fix the problem I have to hit the reset button.  Also once this has occured
I am unable to do a /sbin/ifconfig as any user,  that hangs in the same manner,
 and I have to hit control-C.  It seems to have some correlation to dctrl
having problems monitoring diald's status, but I am not certain if this is a
symptom as well.  I did have this problem once in a great while under Redhat
4.2,  but this is far to frequent to be tolerable.

Any hints or ideas what causes this?  Nothing appears in dmesg or
/var/log/messages.


PS. the in.tftpd service seems to hang as well.