You did right to select 64-Bit, but there are only XP & Vista drivers on the Ion website so I suggest you have a look at:
http://windows.microsoft.com/en-US/windows7/Make-older-programs-run-in-this-version-of-Windows
Your basic steps are:
- Uninstall any existing software for your scanner.
- Disconnct your scanner from your PC.
- Install Vista 64-Bit drivers & other software following advice in above link.
- Reconnect your scanner.
The Ion website specifically says not to use an unpowered USB hub, so it must draw a fair amount of current for a USB device. Bear this in mind. Try disconnecting other non-essential USB devices.
All answers and suggestions are provided by an enthusiastic amateur and are therefore without warranty either explicit or implicit. Basically you use my suggestions at your own risk.