Ken,
I am experiencing the same problem as DongZheng and I have read through the thread.
Is disabling flash mode the only solution to this? Because now, the problem I encounter after disabling flash mode is that this action also disables multiple file upload. After I disable flash upload like you advise, I click the button that allows me to browse my files and it opens a window that says "Choose File to upload" and doesn't allow me to select multiple files. A little problematic considering the button I click on to browse files is titled "Select multiple files (Max 1000M)."
Is there another work around here? Prompting users to install Silverlight doesn't seem like a winning solution either. Please advise.