OS - Windows Vista Home Premium x64 SP2, all current updates installed
DT version - Lite

If your OS has more than a single user and they are logged on simultaneously, the DT user interface is not accessible to the users who weren't the first to log on to the system. Therefore, not all the users can use DT to full extent.

Steps to reproduce
1. Set up a proper OS with several user accounts
2. Launch the OS and log on with one of the user accounts
3. Perform the "Change user" action and log on with some other user account. It's important not to log out the first user, so that they both are in the "Logon performed" state.

Expected behavior
Both the first and the second users have a DT icon in the notification area, and launching the DTLite.exe executable opens the DTL main window

Actual behavior
The user who was logged on first has all the expected things and everything is totally okay. But the second user doesn't have the DTL icon in the notification area, and launching the DTLite.exe executable does nothing.

Additional details
Both users can actually access the images previously mounted via DTL, and they all see the corresponding drive in the system. But only the user who logged on first can access the UI, so the image mounting/unmounting can only be performed under that account.
If you select "Exit" in the DTL notification area icon's context menu, then launching DTLite.exe under the secondary user accounts creates the DTL icon in the notification area and opens up the application's main window.