I’m finally documenting this here because every time I do a hard reset on my phone, I forget what I need to do to tether my phone to my laptop and allow internet sharing.
I actually don’t like my wireless carrier because it uses CDMA technology, which doesn’t allow me to use SIM cards when I’m at work overseas in the summer. But I couldn’t resist it because the monthly plans were so cheap (including data!).
With ActiveSync installed on my computer, use a registry editor such as CeRegEditor and delete the value \HKEY_LOCAL_MACHINE\Comm\InternetSharing\Settings\ForceCellConnection.