When I remove UploadType="IFrame", and I try to upload files, I get a prompt that asks for my user name and password (Unacceptable). However just for testing purposes I enter Admin accounts user name and password... following occurs:

1. I don't get prompted again

2. Next it seems like the first file on the queue is being uploaded (as the in progress circle starts turning next to the file)

3. After a long time, that I realize nothing is happening, I actually realize the entire form including my browser is frozen

 

So removing UploadType="IFRAME" prevents me from uploading files :-(

 

I need to clarify, I'm storing my files into my SQL-Database