I think I found a bug. It happened when I uploaded jpg image file. When I uploaded a file with extension jpg, it uploaded fine, but when I tried to upload a file with extension JPG, the progress bar was still running but no file was uploaded.
The same happened to PNG and JPEG image files.
I wonder is there any way for me to fix this?
I'm using Windows 7 64bit, FF version 3.6.8, latest php, jquery, and uploadify plugin
Make sure you don't have any strtolower() type functions in your backend script. I did a test and it worked fine for me. Are you running it on a Windows server?