client has problem with media uploader

My client is having problems with the uploader while I’m not – why?

While I can access the upload/insert image area with no problems (on Mac) my client (on Windows) hits the upload/insert button and only sees the gray scrolling bar – it never gets to the point where it will allow her to browse or choose an image. Any ideas why she has this problem and I don’t? Or more importantly, how she can get past the scrolling bar to where you can add the image?

She’s running IE8 on XP.