Unable to insert image

I'm trying to insert an image using Firefox 2.0 and I'm unable to. I can try using the Browse button or pasting the image URL in the field, but pressing OK doesn't do anything. I've disabled both AdBlock Plus and NoScript but the problem still exists. What's worse is that when I used IE 7 to insert an image, the Browse button didn't even open the dialog box to search for a file. I noticed there was an error on the page stating access was denied.

Any ideas?
cor