Insol saves the size and position of forms and windows as a preference for the user. If the user moves a form off-screen Insol will set this as a preference so the next time it is opened it will open in the same position off-screen. Occasionally if a user has reconfigured their displays, perhaps moved a screen to the other side, this can also cause some forms to open in a their old position on a screen that no longer exists.
If this is the problem it can be easily resolved by deleting the following key from the users registry, so this is something you can try if the problem is reported again.
HKEY_CURRENT_USER\Software\Exalt Technologies\Insolvency\FormStartupPositions