I run FM 11 and FMS 11 on Windows.
I have an Opener file which requires the user to log in using AD credentials. Once logged in, the user is shown a list of Filemaker files which she can access. Each file name is a hyperlink to the listed file (open URL, using fmp7://). Both files are mounted on FMS 11.
If the same AD credentials are good for this file, she is not asked to log in a second time when she clicks the hyperlink.
That changed when I implemented layout and record restrictions based on the user's privelege set. Afterwards, the user is asked to log in a second time. This happens even when she logs in using the Admin ([Full Access]) account.