My old Latitude D820 recently suffered the purple lines of death. The video went out (dark unit). Luckily, I found an identical working D820 that I could swap hard drives. Problem is that this backup had a modem problem. I figured that I could fix it by swapping the modem from the dark unit. The modems are identical and the one from the dark unit was working just fine. I get a code 45 in the device manager. I get a full description of the modem. Under network connections is says "modem removed" full description(COM3). When I look at the ports under device manager I see only COM1 even after asking to see hidden devices. I tried to reinstall using "detect new hardware". This modem problem existed before and I never had time to figure it out. Now I really want to. I think the modem should be detected at boot-up unless it really is not plugged in. Bad motherboard/sockets?