here is the solution I found it:
Look in your registry, and make sure it only has these entries, and nothing else.
[HKEY_LOCAL_MACHINE\SOFTWARE\Sony Media Software\MC MPEG Plug-In\1.0\License]
(you shoud see letters and digits instead of the Xs here...)
If it is not "CurrentKey" or "InstFlags", get rid of it.
Thank you to myself
PS If you have VEgas Studio the Customer option will not work for you, its only available with the professional version of the encoder, which comes with Vegas.