Inserting existing Image from file cabinet not working?

I am attempting to insert an existing uploaded image into content.  Here's what happens:

1) in the editor, click on the "image" icon

2) click on "link to file cabinet" icon (far right of the "Image URL" blank)

3) the pop-up window opens, however it just say "Please wait...." endlessly 

I waited to see if the folders would eventually load, however, nothing yet... I was able to use this function with no problem last Thursday (this is the first time I've tried using it since then)

NOTE: I tried it in IE 7, Firefox 3 and in multiple groupsites (including while typing this post) - I couldn't seem to get it to work anywhere.