To resize pics on photobucket; you have to click on the photo so it's open, and then click 'Edit'. Once it opens up the free editing software that PB uses, there's a bar at the top where you can click to resize. Then I would just right click and save it; and upload it directly to CP to your avatar if the links are having trouble too. Good luck!
Try going to CP User then going to Edit Avatar then you can highlight custom avatar and click on browse and it will let you download a photo straight out of your picture library on your computer and you don't have to go to photobucket for the avatar if you don't want to. Try that and see if it works.