[wp-testers] HTTP error using new uploader in Firefox and Safari

[Mistah P]

When using the new media uploader on the Write Post page, I'm seeing
inconsistent results from one browser to the next.

Internet Explorer 7.0 works normally.

Opera 9.26 works normally, but only if the Bad Behavior 2.0.13 plugin
is not enabled, otherwise it returns a BB error message with HTTP 417
(this is not a WordPress problem, I know... I'm just saying)

Safari 3.0.4 (523.13) and Firefox 2.0.0.12 fail with messages "HTTP
error" and "An error occurred in the upload. Please try again later."
Screenshot here:
http://i253.photobucket.com/albums/hh61/mistahp/error_screen_cap.jpg

I've tried uploading jpg and mp3 files, using the Add Image, Add
Audio, and Add Media buttons, either one at a time or in small
batches, but those circumstances don't seem to make any difference. It
always works for me in IE and Opera, and never works for me in Safari
or Firefox. I'm using all of these browsers in Windows XP Pro SP2.

Has anyone else encountered this problem? My apologies if this is in
another thread that I missed.