I don't have any slow-down switching from menu to menu on my less than average PC specs.
The Multiplayer screen may be refreshing the screen with online servers, but pressing the stop button works immediately.
You may need to make sure you completely uninstalled/deleted the previous version and cleaning your PC of it 100%, before installing the retail copy.
Install the retail version of BF2 on your system without any trace of the prior version.
* Run the BF2 Uninstall
* Reboot your PC
* Delete the whole directory after the uninstall:
C:\Program Files\EA GAMES\Battlefield 2* Delete the User directory also:
C:\Documents and Settings\your_name_here\My Documents\Battlefield 2* Reboot your PC
* Make sure your Video & Audio drivers are updated/current
* Reboot your PC
* Install BF2 and then Special forces (if you have it)
* Download and install the
FULL 1.21 patch* Reboot your PC
* Kill any uneeded tasks running in the background (anit-virus, firewall, etc..)
* Launch BF2
Your PC specs would help diagnose the problem, if you still have problems re-installing BF2. (CPU, RAM, Video specs, OS, etc..)