Click Start then Run and type regedit and click "Ok". Navigate to: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\CDRom in the left pane and look at "AutoRun" in the right pane, under Data, what is the last number in the string? (should be a 0 or 1) If it's a 0, right click on AutoRun and choose Modify. In the Value Data box, type 1, select Hexadecimal and click "Ok". Exit the registry editor and reboot.
Let me know what you find.