I am getting the error message from the title:
The following boot-start or system-start driver(s) failed to load: cdrom
in event viewer during startup, and as a consequence Windows 7 doesn't recognize my cdrom. How can I fix it?
Microsoft says that for Windows 7 that the Hardware and Devices troubleshooter will fix it, but you might try the Win-XP steps (they worked for me):
Note these steps also work for the Event log entry: