Ok, hope the following will help those who might run into the same problem.
(1) Cause: Exact cause is unknown, maybe is caused by corrupted registry
files due to remove and re-install applications.
(2) Symptom: Yellow exclamation mark for Microsoft Tun Miniport Adaptor #2
in Device Manager.
(3) Short-term solution: Removing TCP/IP version 6 may also remove the
adapter, and thus the conflict. But this is not a "solution" per se.
(4) Long-term solution as follows:
Thanks for the tips and discussion in here:
http://www.testmy.net/topic-2373
by Bazza25 who mentioned related driver info: (tunmp.sys
c:\windows\system32\drivers
netip6.pnf c:\windows\inf
nettun.pnf c:\windows\inf)
Note: My solution involves "delete" registry files so use it at your own
risk.
Step 1: Remove TCP/IP version 6 protocol and reboot.
Step 2: In Normal mode, move tunmp.sys from its current location and another
location.
Step 3: Boot into Safe Mode (without Network)
Step 4: Run "Regedit" and search for every reference to Microsoft Tun
Miniport Adaptor and delete them (backup first) Note: You may also find
some entries in ControlSet2, ControlSet3... and you may not delete some of
them, but it's ok. The most important thing is to delete those entries in
the current controlset.
Step 5: Go to Device Manager and remove Microsoft Tun Miniport Adaptor
(Note: If you did not delete registry entries and did not move tunmp.sys to
another location, you can not remove this adapter as it will be preloaded).
Step 6: Boot to Normal Mode
Step 7: See if you have other conflicts and all other Network adapters have
been properly recognized.
Step 8: If so, Move tunmp.sys back to its original location. Note: Just for
precautious, turn off your AV and Firewall and disconnect from the net.
Step 9: Now you can add TCP/IP version 6 protocol back without any error.
Additional notes:
I guess the issue is that, unlike other network adapters, Microsoft Tun
Miniport Adaptor can only have one entry and cannot have #2, #3, and so on,
or otherwise, it will mess up the driver version even using both are
pointing to the same file - tunmp.sys. I also noticed that at one time,
Adapter #2 did not have conflict but it was the first Microsoft Tun Miniport
Adaptor that had the yellow exclaim mark. So based on those, I decided to
take a more drastic approach to delete all registry entries and to "cheat"
Windows that there is none in the system. So when I added back TCP/IP
version 6 (which will automatically created this adapter entry), it will not
have #2 but only one.
Hope this helps.