Same issue here, and have not been able to resolve it.
I use a different method with SP2C installations vs the others.
I run a NewSid Program which changes the SID to avoid the network connectivity issues stated above.
http://www.microsoft.com/technet/sysinternals/Security/NewSid.mspx
I then created a patch file to disable the WPA. That deletes the following lines
C:\windows\system32\WPA.OLD
C:\windows\system32\WPA.BAK
C:\windows\system32\WPA.DBL
and changes the registry settings:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\WPAEvents]
"OOBETimer"=hex:ca,82,b8,55,d4,04,b5,cf,cc,5b,24,00
Upon rebooting the machine you will be able to reactivate with a new-cd key by clicking, telephone, then new product key.
I called MS to try and resolve the issues with C keys on B installations, and was given the run around for litterally 4 hours, even after agreeing to pay the fee for tech support, and ended up rewritting the automated program used to quality check machines to use this method as opposed to the WPUpdate tool.