Hi AngusMac,
Sorry that there wasn't a option to disable the Smart Install from the EWS.
I have been checking into this.
Make sure you are running the uninstall from the CD or Program files.
This way it should remove all the registry files.
Make sure the printer's USB cable is disconnected.
Here are the steps to run the uninstall from the computer or the CD.
To uninstall from program files:
Go start and select computer.
Select the C drive.
Select program files or program files x86.
Open the HP and printer name folder.
Select uninstall.
Uninstall From CD:
Go start, computer, right click on the CD for the printer, left click open in a new window, double click on uninstall.
Remove the drivers from server properties if they are still listed.
Go to start, devices and printers.
Highlight any printer.
Choose print server properties across the top.
Click on the drivers tab at the top of print server properties window.
Choose the printer you want to uninstall and click remove.
The next screen will give a warning, letting you know that deleting the driver package will remove it from the system. Click yes to say that you are sure you want to do this.
Then in the devices and printers window, right click your printer and remove device if the printer is still listed.
If the printer is listed still in device manager or the registry we would have to delete it there also.
Keep me posted.