Just to throw a wrench into the system . . .
I am having the intermittent problem of the Alt-tab window quickly disappearing that some have described.
As with others, this problem has appeared over time, and sometimes works properly.
The catch is that, in my case, it has nothing to do with
any of the issues identified in this thread:
No gadgets are installed, and Sidebar.exe is NOT running (verified in Task Manager).
I am using IE8, and have Never had IE9 installed.
I do not have Intellipoint running nor is it installed (although, coincidentally, windows update actually tried to install it since I started reading this thread).
I am seeing some things that have not been described here - am wondering whether they are common to others - here is an example:
I currently have 17 windows open, and if I Alt-tab from this screen (Firefox), it will consistently exhibit the behavior. If I alt-tab while on the Adobe Reader screen, it works correctly
Every Time.
Ten minutes ago, the same could be said about the Firefox window - alt-tab worked correctly whenever the FF window was in front.
Now it never works correctly with FF in front - the one difference that I can think of is that some other windows have been closed in the meantime.
BUT, there is still a difference in functionality when doing alt-tab from the FF screen - it takes significantly longer for the alt-tab screen to disappear (maybe 1/2 second) than when doing alt-tab from other windows (about 1/10 second).