Update:
Offical Alt-Tab Fix from DICE for BF2 1.50 is out, what affect PR 0.874 also
This fix makes AA and Widescreen possible, without freezing if you are switching to the Desktop
* Download the attached file
* Extract it into your Battlefield 2 install directory (you must have v1.50 installed already)
* When prompted accept that you want to over write the existing file
* In My Documents go to Battlefield 2\mods\bf2 and delete the cache directory
* Run BF2 as normal