Frank,
I am sorry you are having this trouble. Here are a couple of things to look at.
First, you might try inserting the USB drive into the iFly with the power off (unplugged). Then with the USB in the iFly, power it on. Touch the Update button on the start screen. You should be prompted to Update from Wi-Fi or Internet (if connected) or from the USB Flash Drive. Select the USB Flash Drive and the update should proceed. I've seen where inserting the USB with the power on may not recognize the drive. By powering the iFly on with the USB drive inserted, it essentially forces the USB for be found prior to other processes.
Also, that brands, sizes of USB stick are you using. We recommend 2 or 4 gb versions of Sandisk, Lexar, Samsung, but not PNY. Larger USB cards are usually formatted in a exFat format and the iFly needs Fat32.
Also, iFly Connect only need IE for the initial install. After that, you would never need IE to run. You would have an iFly Connect program the Programs Folder (Adventure Pilot Folder). Just put a shortcut on your desktop and run it from the icon. It does not use IE. Just to install.
You can set the iFly to boot direct to Navigation. It is in the Setup menus from the Start Screen of the device. Turn iFly720 on, then Setup -> Tools (wrench & screwdriver icon), The first tab will give an option to boot to Main Menu or Navigation, select Navigation. Note: this will bypass the start screen so the setup, internet, multimedia won't be there. You'll just have to exit the iFly application to access that.