Dear Lazyweb: I have a mystifying Linux problem.
To begin the tale, I've been running Mandriva Linux on my laptop since last October with considerable satisfaction; I use KDE and the Metisse 3D window manager. However, I had to disable the ACPI power management support to get the thing working; eventually I grew tired of this and decided to sort it. Research suggested that the solution might be to update the BIOS; a check showed my machine was running version 4 and the current one was version 11. So I booted in Windows, got the new firmware, reflashed, and rebooted in Linux; and the ACPI CPU tuning, suspend-to-RAM, and suspend-to-disk began working. But later that night I had a crisis - the thing will not boot with ACPI enabled from the Mandriva console, and the KDE desktop wouldn't start.
Eventually I was able to uninstall the whole KDE and reinstall it, which got us working. But the Metisse desktop doesn't work; enable it, and the X server crashes on login. Trying to startkde from a command line gives what appears to be a common error, "$DISPLAY not set". Without Metisse, either no 3D or Compiz works; setting ACPI=ON at the kernel switch allows some but not all functions to work (still no brightness control, but CPU tuning, shutdown, and suspend).
There was an Xorg update on Friday which I hoped might change things, but no. Today saw a big KDE update, but I haven't experimented on it yet. Any ideas?