Think it was Sharkbait that released the alt+tab fix. This fix does nothing execpt overide the file "dice.bik" within the same file inside the folder:

Battlefield 2142\mods\bf2142\Movies

This one worked for many players so the best solution to prevent Alt+TAB error in BF2142 vanilla is not to disable the intro movies. As far as I can see there is no "Movies" folder inside the firstrike directory and that might cause the problem. What about contacting Sharkbait from BF2142.se who released the hotfix. Or maybe DICE directly?

All I can say is that this error is PITA. As an editor I'm so used to switch between the game and other programs / tools that I've been stuck over a dozen times now. And even if I realize that I can't switch back I'll have to terminate the game via right click and start it again. And think about the messenger and all the other stuff people like to use / look at while a map is loading. So a hotfix or any solution without having to install Riva or any other third party software would be much appreciated ^^