Make sure stdriver64.sys is actually not being loaded anymore.
right-click on "My Computer" –> "Manage", go to Device Manager
or
go to the Device Manager from your control panel.
click "View" –> "Show hidden devices"
open category "Non-Plus and Play Drivers"
and go down the list checking to make sure it’s not there. If you don’t recognize something, you can double-click on it, go to the "Driver" tab, click on "Driver Details…" (which only shows up if the driver uses .sys/etc files), and then you can see what .sys files it uses.
Obviously you want the one with stdriver64.sys, if it exists. Right click on it in the list in Device Manager (not Driver Details), and go to "Uninstall".
You might not find it in there, but I thought it’s worth a shot anyways, in case the uninstaller for it screwed up (you did use the actual uninstaller for it, and not just remove the software, right??).