Might as well change my username to Aresura, mostly because Josepania as I had planned it has been put on indefinite hold due to, of all things, RP, and I don't want to keep confusing people.
When i post images I usually just post a link and that is enough for greasemonkey. Try and go through your images and take those tags off if it's not too much trouble. I never use Image tags.
EDIT: the link is usually a direct link to the picture.
I've done that, and, funny, when I edit them, the images appear, but when I see the final post, they do not. I dunno if that's a problem with greasemonkey or not, but it's wierd...
It could also be your browser version, I know when i upgraded to firefox 4.0 it didn't work so i just went back to 3.6 since i dont know how to change the code.
Not all images work. For example, if you are trying to use images from wikipedia or something, it won't display. You need to use images from imageshack or photobucket as far as I can tell.