Also take a peak in devices , in harware tab, in the system folder in control panel...look for any red X or exclamation points
also try the dvd player in safe mode...reboot the pc and when you see the first glimmer of the pc coming back start taping the F8 key, you will get a menu , select safe mode.
also how is your pc running in general...slow, long time to boot or shutdown
may also be infected with viruses , trojans. spyware..this can cause symptoms you have also.