I have a display problem in KDE, sometimes at startup everything goes black except the mouse. It only happens in the Login screen or in the boot screen. Lilo displays correctly and once I have loaded KDE there is no problem.
I think it happens because Linux detects something else as a secondary monitor. Also I have noticed that this happens only when I Shutdown the computer with the AC adapter unplugged and I turn on with the adapter plugged.
My Laptop is Toshiba and my Os is Linux Slackware 14.
Any hint is helpful, for example how can I diagnose by myself the exact problem.