I had some luck in solving my problem, and I hope this helps. A good place to start is at www.driverguide.com. This site requires signup but is free. On the homepage go to drivers tutorial. This gives an excellent summary of the problem and suggested paths for fixing it. Using this advice, here is what I did: Click Start on the bottom left of the screen and select Windows Update (the top entry on my menu) In the next sceen click Support Information Click on Windows 98 (or whatever system you want to upgrade-mine was Windows 98) Click on Download Software Click on Microsoft Windows Update This brings you to a screen which apparently inquires your computer and then lists possible upgrades that might be useful. At the bottom of this list I found the following message: “Windows Uddate has detected that you have the following hardware devices installed on or attached to your computer. Windows Update has an pdated version of the device driver siftware that enables you to use this hardware with Microsoft Windows Promise Technology-Storage 49 KB/ Download Time < 1 min Promise Technology Scsiadapter Driver Version 2.0.0.28” I downloaded this software and rebooted. The error messages under Performance were gone and replaced with one that said that the computer was optimally configured. In the Device Manager, the PCI Mass Storage Controller was no longer listed, but at least there were no devices with a yellow and black exclamation point. The computer seems fine, and the PCI Mass Storage Controller has not re-appeared on rebooting, something that occurred when I tried to remove it before. Hope this helps. I realize that the root of the problem could differ in other computers PS: I posted this message in another forum called PCI Mass Storage Controller because I was having trouble posting it here