Flash Uploader for Media Error

Hi – can someone tell me why this is happening:

This happens when I upload media with the Flash uploader.

Note: I’ve read the forums, searched, tried the solutions provided (htaccess, etc) and even contacted my web host. No one can find a solution.

It’s not the file sizes, other plugins, all the usual stuff. I’ve tried it all and I’m at the point where I’m just frustrated and turning to the community for some help.

I have the lastest flash, firefox, wordpress – all that stuff. I have no idea why this is happening. The Browser Uploader does work fine, by the way.

Any help would certainly be appreciated! Thank you!!!