Scanner and Cameras Events Tab Error

I recently installed Nuance PaperPort 11 for Vista onto my computer. I also
installed the Vista drivers for my HP ScanJet 5590.

I should be able to assign the five buttons on the front of the 5590 using
the Events tab on the Scanners and Cameras Control Panel applet in Vista to
launch PaperPort from any of those buttons. I should then be able to assign
particular scan profiles for each of those buttons from the Oprions/Buttons
menus in PaperPort. The latter cannot be done without the former!

However, when I attempt to change the Action on the Event menu in the
Control Panel applet, I receive an "Event registration failed" error that
states, "The attempt to change the registered event handler failed. Please
make sure the device is turned on and connected properly."

The device is turned on and connected properly and functions. I have
attached a snip of the error and screens to this message. If someone has
experienced this and has a solution, please reply. Thanks!