Temp directory using virtualized path on some computers

In my Silverlight application I'm using regular SaveFileDialog for prompt user to save some file.

The problem is that on some Windows 7 computers, if user use IE in protected mode, and try to save to for example on desktop, path for saving ends up like this:

C:\Users\<user>\Appdata\Local\Microsoft\Windows\Temporary Internet Files\Virtualized\C\Users\<user>\Desktop

Does anybody know where I can find flag or value indicating that this path will be used instead of regular one on windows?

Thank you