There is no Scanjet G4000. There are G4010 and G4050 models, both of which have drivers included in Windows 7.
To the OP:
I'm having the same problem. (Off for the next 2 weeks and doing several clean W7 Ult 64 installs). There are several links that appear to be worth watching:
I always do trial installs a couple of times before a final install - I'll try the Windows update drivers and see what happens. Will also try the apps in compatibility mode.
In Vista, I tended to use VueScan mostly anyway (though it's not free):
*** Did you try Windows Update for the drivers??
* Please try a lower page number.
* Please enter only numbers.