406 error on firebug only

Im using a script from this guy

A. Valums http://valums.com/ajax-upload/

Everything is fine until the file has finished uploading and i get a 406 error on the firebug(ONLY). when i right click the link on firebug and open in new window, the file does exist and does what i expect it to do.

t开发者_如何学Che page on firebug says

Not Acceptable

An appropriate representation of the requested resource upload.php could not be found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

but when i see the page on a new tab it works fine and returns the right thing, that script on A. Valums has ajax requests btw

UPDATE

Host            www.example.com
User-Agent      Mozilla/5.0 (Windows; U; Windows NT 6.1; en-GB; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13
Accept          text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language en-gb,en;q=0.5
Accept-Encoding gzip,deflate
Accept-Charset  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive      115
Connection      keep-alive
Content-Type    application/octet-stream
Referer         http://www.example.com
Content-Length  192378
Cookie

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Look at the HTTP headers. Your JavaScript is likely adding an Accept header that the server thinks it doesn't have a suitable type of data to respond with.

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It was a server error.something called "mod_security" which needs to be disabled and I have no clue what it is but ask your hosting provider they should know about it if you experience the problem :)