Yep, I had the very same issue and trawled the internet to no avail. Also trawled my attic for scanners I'd laid by so I could dump the monolithic 9110, but guess what, my HP scanner wasn't supported in W7 either!
Still I have got the 9110 working by being bad. No guarantees it wont fail down the line, but here is the fix...
Plug it in and let it install from windows update, then disable install from windows update (in device installation settings, in advanced system settings) . As you said the printer driver is fine. Then go to Printers, right click on the 9110 icon, properties, click on the hardware tab, and highlight the scanner, then click on properties. Click on the change settings button, click on the driver tab then update driver button. Select update from my computer, then let me pick from a list...Then pick imaging devices, HP, and here's the bad bit...select the HP Officejet V45. The hardware scanner must be mapped out the same because it installs the driver and you should hear the scanner respond straight away. I tested it with the Windows 7 fax and scan.
Good luck!