If you are running Windows 7 64Bit, you'll most likely have to run humminbird pc in compatibility mode.

To try this, go to start, programs, find the humminbird pc start menu item, right click on it, select properties. Then click the compatibility tab. Click the checkbox for "run this program in compatibility for :" Windows XP (service pack 3) should already be selected. Just hit the "OK" button. This will apply the changes.