gdm crashes switching user. former "endless drumbeats" thread.

[Vitorio Okio]

I'd better open a new thread, since the endless drumbeats I complained is 
just an audible symptom of a dipper problem.

Lately I had 2 problems appeared after almost 2 years of running Hardy on 
Asus P4PE with ATI Radeon 9550. Both problems showed up infrequently, 
about 1-2 times a month and did not look related at first.

1. Sometimes I could get an endless drumbeats sound after switching a 
user and a subsequent successful login.

2. Sometimes in a middle of a session my monitor could get black with "no 
signal" message on it.  The only way out of it was a reboot. 

Troubleshooting the second problem I found an odd problem with Xorg-ati 
driver: "direct rendering" was Off with a very low frame rate. 
Reinstalling driver related packages seemingly fixed things.

Today, after I logout the second user and get login myself I run 
glxgears, just to check, and found the problem was back: no "direct 
rendering" and low frame rate.

System log showed gdm running at the background in an loop attempting to 
login using user name "unknown" (?) and reporting "Writing failed session 
attempt utmp-wtmp record" endlessly. This was certainly providing with 
the damn drumbeats.

Again, at this point a session for the second user was closed and I was 
successfully login.

Any links that could help, any suggestions folks? Unfortunately I was not 
able to find anything really useful so far.