ok... well... looking at your avatar means that you've exceeded your bandwidth obviously, lol. this means most of the time that you've used the limit to how much internet you were allowed for that month. some companies, especially in europe (so americans won't understand this), only allow you to upload/download so much information per month from the internet.
i'm assuming that even if you go to imageshack, you're going to have the same problems because it's not photobucket's fault. it's your internet access doing something - at least that's what i think will be the answer you finally get.
all sites like imageshack or photobucket will have a limit if you're not a member paying for their services, so the same could happen with this as well.
to be honest i don't really understand how it's... i don't know, but if you've recently uploaded some pictures and this has happened i would try deleting some definately.
yeah, think you'll need to wait till next month. =*( but all sites will be like that, not only photobucket. maybe just keep 2 accounts - one with photubucket and one with imageshack in case that happens, lol.