Can't upload images

I am trying to use either the flash uploader or the browser uploader, but whenever I try to upload a picture, nothing happens. I use the flash uploader and select a file. It says “crunching…” and then .. nothing. It says “after a file has been uploaded you can add titles and descriptions.And there is a “save changes” button. But no photo shows up. I try the browser uploader, select a file and click “upload” and the result is a blank screen.
I’ve tried this with Firefox and IE. Same result. uploads directory permissions are at 777 for now and still no go. Any ideas?