If you want it for your avatar, just host it elsewhere instead of here. For some reason when you host it here and the software tries to resize it, the animation gets nuked. Doesn't happen when it's hosted elsewhere.
If you have some other purpose in mind, I'm about 99% sure that Serif PhotoPlus can resize animated gifs without losing the animation and it's free.
Edit: testing with Photoplus.
Edit #2: Yep, works fine. Photoplus is fantastic, it's a poor man's Photoshop.
Edit #3: the little guy's sign refers to me (for not checking before I posted this) and not to you.
-S