I have a Windows 7 Enterprise x64 machine both at work and at home for some reason the UAC dialog windows like to pop UNDER all of my windows instead of on top of everything, is this a bug? It's not consistent whether it will pop over or pop under.
If you have the program that triggers the UAC dialog active, the dialog will pop up.
If some background program triggers the dialog (for instance an installer which you've alt-tabbed away from) the dialog pops under.
At least that's my experience
Update: When the uac setting is in one of the two "higher" settings. The screen is suppose to deem, and the only accessible windows is the uac dialog. That's why you should check that its in the settings I have suggested.
Make sure that your uac settings are in the "default" or "always notify" settings.