Mac upload error using AD account

Hi,

I'm evaluating FileVista & this is an observation I noticed.
When logged in using an AD account and uploading using Mac's Safari or Firefox, I will encounter upload error. However, other file operation like folder creation & file download worked fine. 
When I logged in using FileVista admin account, uploading works fine.
Is this an issue with AD?

Flash plugin does not properly handle HTTP Authentication mode. Please first try using Basic Authentication in IIS and see the results. If you still have problems, you will need to use Browser upload mode. Please force Browser upload mode by adding this line: 

<add key="UploadMethod" value="Browser" /> 

to
FileVista\App_Data\FileVista.config. 

Using the browser upload mode works. Thanks!