My mates son has just tried to install some software onto his new PC. After a reboot he got a message that went something like "the registry is corrupt and does not match current configuration" and now he has no CD drive. In device manager the CD drive has a yellow exclamation mark. We have uninstalled the device - switched off - disconnected the drive -rebooted-switched off - connected drive- rebooted and xp says found new hardware identifies the drive etc but says there is a problem with the hardware and it didn't install properly - yellow exclamation mark is back. Have tried this with a different cd drive with the same result. The bios finds the drive okay. Does anyone have any ideas short of trashing the thing and starting again.