I have a Dell Studio 1735 laptop and a Samsung SyncMaster 223BW connected via an HDMI - DVI cable. The external monitor worked fine for months, then one day simply stopped working when I rebooted.
The cable works, I can get the monitor to work via a VGA cable, the Samsung monitor is fine and there are no display issues for my laptop screen.
If I connect the monitor via the HDMI - DVI cable the monitor seems to 'know' it's connected to something as the screen goes blank (as opose to the 'finding signal' screen) and the power light flashes, which indicates it's not receiving a signal when connected. In the Display dialog in Vista a second monitor is shown (albeit at a tiny resolution) and I can enable it, but as soon as it's enabled the second monitor greys out. Same in Catalyst Control Center. Nothing shows on the Samsung monitor at any point. I've tried FN+F8 which used to toggle my display, but again this has no effect.
I've tried updating the ATI Radeon driver and searched for associated up to date drivers but Vista tells me I have the latest ones.
It's weird because it was working fine and now it's just died. I hadn't added anything to the system or changed any settings when it decided to go wrong.
My extensive research into this has revealed a few similar problems and I remember reading one person say that there can be conflicts with Microsoft Intellmouse / IntelliType software, which I used but have since uninstalled. This made no difference. Other than that I'm stumped.
Any thoughts would be hugely appreciated.