This has nothing to do with edge scrolling, it's your middle mouse button, depress it and this is the functionality you get in game, just like if you depress it over a web page.
It sounds to me like you're clicking it while the game loads. Key press during startup results in a stuck send, pressing it again unsticks it.
If you're not, then you have either a buggered mouse or buggered drivers. Try a reinstall instead of putting the same driver file back.
