An alternate solution/fix... In FF3, You can retrieve file's full path in a text box instead of file browse box. And that too... By drag/dropping the file!
You can drag drop your file into a text box in your html page. and it will display the file's complete path. This data can transferred to your server easily or manipulate them.
All you have to do is... Use the extension DragDropUpload
This extension will helps you in drag dropping files into your File Browse (Input file) box. But still you wont able to get the file full path, If you try to retrieve.