I've been playing D2 with my friend, and her laptop (new with Vista) has been being a piece. The disc spun, the mouse became the disc-read icon, and nothing happened. I was furious, and started clicking this and changing that, running it again and again and again. Finally, after closing [bleep] out of her task manager, I found the culprit. Once I stopped "Desktop Window Manager", everything worked fine. Until it booted back up again a minute later.
I checked around and found a way to stop this once and for all.
Under search, type in 'services.msc' and hit enter. It'll probably prompt you and need your permission to continue, as Vista so often does. When you get into the services menu, scroll down until you find "Desktop Window Manager Session Manager". Right click on this, go to properties, and change startup type to disable.
If you're looking for a reason to disable it, there's a very helpful account on exactly how awful it is for your computer here:
http://www.petri.co....ance_issues.htmEven if this doesn't explain why your Diablo 2 won't run, it'll definitely help your system until we all decide we'd be better off reinstalling XP.