I just installed an HP DVD 300i drive 4x DVD+RW I had from my pc. It runs when the computer is first turned on but once the OS is loaded it's totally unresponsive. I thought it might not be compatible but googled and it works in other people's Macs. I tried the CD-ROM I pulled from the machine and it works fine. I'm at a loss of what to do next. I'd appreciate some help.