really stuck and need help!

Hey there,
I manage a site for a bunch of clients and I recently installed WP 2.0 and love it, but there’s a problem that’s causing all of my clients trouble. I’ve read through all the old posts and haven’t found it anywhere.

The site is http://www.beauxpaint.com/sketchersroyal/

Here’s the problem: I upload my picture to display, I click on it and set it to upload the original. However, if I click and drag it into the post or if I click “send to editor” all that shows up is a bunch of text or a link to the file, but no image.

The weirdest thing is that I use firefox 1.0.3 and I don’t have this problem. My clients on this server, however, aren’t using firefox 1.0.3 They’re using Safari, I.E. and firefox 1.5. For them, the image browser doesn’t work as mentioned. I’ve researched this too by doing it on machines with those browsers and it doesn’t work. What’s going on?

I would really appreciate some help. Thanks.