I have three WP blogs at the same place. On the newest and third blog the major difference is that WP is one level higher in the root for the domain. The web provider throttles FTP uploads so I am limited literally to uploading six files at a time. Uploads stop and resume. This could be causing corrupted files.
When I hover over the add image button I see the alt test but when I click on it nothing happens. No box pops up allowing me to upload an image as it does on the other two blogs. I also noted that the +Add Category link does nothing on the post page. Inj order to upload images I use the media upload button on the main menu.
The same symptoms exist with no plugins loaded. I run Bad Behavior on all three blogs but disabled it with no change. Is there a clue as to which file might need to be uploaded again so I can start working in that directory? It's really frustrating this six or fewer files at a time thing. Sit security is now a royal pain for the customer.