I've received two reports of registry corruption on Win2K when the TAP-Win32 driver is uninstalled and then reinstalled without an intervening reboot. In one of the cases, someone attempted to uninstall the driver using the driver manager, then they attempted to reinstall without rebooting first. They reported that this caused the TCP/IP bindings to be corrupted, and rebooting did not fix the problem.
This issue only exists on Win2K, not XP, and appears to be a Windows bug. Apparently when Windows uninstalls the TAP-Win32 driver on Win2K, the uninstall is not finalized until reboot. If you then try to reinstall before rebooting, the network bindings can be corrupted. This bug appears to be fixed on XP, as you can install, upgrade, and uninstall the driver multiple times without needing to reboot. The safest approach is to always reboot after an install, upgrade, or uninstall of the TAP-Win32 driver. James