In my short time here I've seen several folks have problems posting pictures. I've also seen advice given that you should use a hosting site and link the picture. I wish I could find the name, but I downloaded a cool little picture resizer. All you have to do is right click on the picture file and a menu pops up asking you what size you want it reduced to. From there it's just a matter of attaching it to your post. I googled it and it looks like there are lots of similar programs out there that are free. Hopefully this is helpful to someone!
Scott