I was trying to connect a HP monitor ZR 22W (very nice image quality!) to my iMac running OS X 10.6.6. After running a wire between them (mini DVI to DVI), I inserted the monitor's CD into the iMac. The CD was read but the files could not be opened. The error message was to the effect that OS X could not open a file starting with "macro." Meanwhile, the HP was showing the OS X opening screen and nothing else. I disconnected the iMac from the HP and later on I inserted a regular DVD into the iMac's drive and got an error message that no valid device could be found to play the DVD. So, two questions: how to reset the iMac so that it can find the DVD player again, and of course, what to do to open those files and use the HP as intended. Thanks.