I've been having this problem for some time, it's not important and the cosmetic appeal of Windows Vista Aero scheme is hardly business critical, I just hate not knowing why something doesn't work as expected in Windows.
The problem is, every now and again (possibly 3-4 times a week) at unpredictable times, Vista decides I don't really want to view windows contents while dragging the window really and permanently nobbles the option. I have to go back into Display settings to re-enable and that hacks me off.
Maybe it's a certain application that runs in compatibility mode, although I'd have expected a popup message that this was happening. Some other sufferers suggest it might be related to some hidden virtual memory or physical memory threshold.
I've yet to find the cause on my laptop but here's what I did do. Removed system permission on the registry key used to track the feature. Hah, try and disable it now Windows Vista!
The key is HKEY_CURRENT_USER\Control Panel\Desktop\DragFullWindows
I cloned the permissions rather than inheriting from parent then moved system and administrator permissions to read-only. It seems to be working so far!
