Ever since I terminated my old file server account, I've been forced to rely on Imageshack for my image uploading needs, since my ISP is being a little bitch about webspace. Unfortunately, when I try to link to the hosted image in my profile signature (through Forum Profile, Modify Profile) it just doesn't seem to take. Linking to other domains seems to be no problem. The image is 197x69 px, well within the size constraints, and I've tried both .png and .jpg; it doesn't seem to make a difference. Eventually I was able to circumvent the issue by uploading the image to the wiki and linking to it there, but I'd really rather not make this a habit.
Does the forum code blacklist free image server sites like Imageshack and Photobucket?