Intrepid. Desktop flashing on and off after login

[Nigel Henry]

You know how when you change the resolution, the desktop blacks out and then 
returns with the new resolution, perhaps with a click of a relay in the crt 
monitor, well I'm getting that continually, like a flashing neon sign.

I do get the same sort of behaviour with other distros on this machine, but is 
limited to one or two on and offs, then the desktop is stable.

I've just installed both Ubuntu 8.10, and Kubuntu 8.10, on this machine, so as 
to perhaps help with sound related problems with Intrepid. This is the 
desktop i386 version, but on 64 bit hardware.

When I boot Ubuntu, there are no problems as far as the GDM login screen. I 
login, then I get 2 or 3 on and offs, with clicks from a relay in the 
monitor, then the Gnome desktop displays ok, with no further problems.

When I boot Kubuntu, there are no problems as far as the KDM login screen, but 
when I login, the desktop opens, then blacks out, then opens, and blacks out 
ad infinitum. I perhaps get 3 or 4 secs of desktop, then I lose it, then a 
second or so later it comes back, accompanied by clicks from a relay in the 
monitor.

/etc/X11/xorg.conf has no specific settings in it, either on Ubuntu, or 
Kubuntu, and as dpkg -reconfigure -phigh xserver-xorg, does not appear to 
available anymore, i'm a bit stuck.

Any suggestions for a fix, no matter how wacky?

I'm currently downloading the post install updates for Kubuntu, and perhaps 
some update will resolve the problem, but I doubt it.

ironically the sound on both Ubuntu, and Kubuntu works fine with the hda intel 
card that is on this machine.

Nigel.