Basically there was a big patent licensing issue between Unisys and Compuserv with the LZW compression used in GIF's. These assholes were trying to get everyone to pay them a license fee for using the file format. So some companies decided to just drop GIF support.
And that is why your GIF doesn't work. Or maybe some other reason, I'm just guessing.
Did you alter the size or anything else? Looks like you tried to make it bigger.... animated gifs often stop working when modified without the appropriate software.
some of my gif files work as avatars and some dont, i thought it was down to the filesize and dimensions but one of my ones that doesnt work is only someting like 24kb, ive tried resizing in irfanview but the resizing option in the toolbar isnt available when i open .gif's, what is the appropriate software to resize gifs?