Media-uploader.php breaks

I too have had problems with the 2.5.1 image uploader. Thanks to Otto42 and others, the uploader now works properly, but the insertion function is still broken despite all the fixes that have been proposed.
On my XP system, selecting Add Media brings up a screen that contains the options of either uploading image files or inserting one by entering a URL. There are no tabs across the top for Choose Files or Media Library. If you use the Upload function, you can upload the file and it shows up in the Media Library, but you can not insert it into the post with the form. You must close the form, go to the post and insert the image by using the Image Insert button and typing in the URL. You can also insert the image using HTML code, as long as you know the URL.
If you type in the URL of image-uploader.php in the address box at the top of the browser (any browser), the uploader page is fully displayed with tabs at the top and all other features operational. That leads me to believe that there is nothing wrong with the form, but something in the Add Media function of the post that is preventing it from fully loading. Hopefully, the WP gurus are getting the upper hand on this vexing problem.
Don Schaal