sorry for the long response, but I managed to solve this problem by doing these steps:
- uninstalled ZoneAlarm Free Firewall (this was likely the cause for my Teredo driver to disappear)
- followed the steps at this link: Teredo Tunneling Pseudo-Interface Needs Reinstalling in Windows 7 - Cable Forum
By doing this, my teredo driver was back into the spotlight. I then reinstalled ZoneAlarm and so far, no problems were found. If there is anything arises, I will let know.
This issue will be marked as "SOLVED".