Mysterious monitor behavior just after boot

[GottaBuild]

OK, I'm new to Linux, but I do have 20 years of programming, and I am still totally baffled.

I am running Knoppix live CD (this also happens with BeatrIX live CD). My PC has NO hard disk. I have a USB pen drive and a DSL connection. About once every 3 or 4 boots, the following strange thing happens:

The POST goes fine, the keyboard works fine because I enter a BIOS password and it is recognized, the boot goes fine for a while, and the boot messages appear fine, with colors and everything, etc. WHile the messages are displayed the monitor image is crisp and perfect. Then, just before the Knoppix desktop should appear, the monitor screen goes black, then starts painting stripes of color on the top half of the screen. The bottom half gets different colors. There is no symmetry to the patterns. If I start moving the mouse (no mouse ponter is visible) I can change the colors along the bottom half of the screen. Left alone, the colors gradually change but with no perceptible time pattern. Some mouse click, specially along the bottom of the screen trigger some action either in the form of color changes, or CD drive movement. At times I can hear the CD drive working even ewithout any mouse action. The CD and DVD drive lights stay black and don't respond to manual pushing of the eject buttons. The PC's on/off switch does not respond so eventually I simply pull the plug and reboot, and usually everything works just fine. When the boot goes well, the monitor works fine even for 24 hours or until the PC is turned off, .

This PC was running Windows XP service pack 2 for years and untill very recently, and this phenomenon never happened under Windows. The PC is presumed to have picked up all manner of malware, having been connected to DSL 24/7 with nothing more than Norton and WebRoot to protect it, and it was used to test innumerable software trials downloaded from the net. The hard drive has been disconnected and the BIOS reset by disconnecting the battery, but not flashed. The PC is a DELL Dimension 2350 with 1 GB of newly installed memory.

Is this a video EEPROM rootkit for windows going nuts with Linux OS? Or is there some known Linux thing that fits the description? Something obvious to all except the Linux newbie?

[ckamin]

It might be the way hardware is detected or the video drivers are selected. It might change from one boot to another. Just a thought. I would try using some of the cheatcodes to specify the video parameters while booting. Selecting the drivers, etc might give you a solution. There is a list of cheatcodes and some explanations located under the "Documentation" link at the top of the page. Another one you might try is noddc. I'm not sure if it's listed, but it has solved a few monitor issues for me in the past.