I had a similar problem activating the MPEG2 Codec.
I was never able to get the activation numbers using Auto-Activation. I was able to finally get the activation numbers by using the manual instructions posted by John at Roxio. At first it did not work but when I disabled my virus program and following John's instructions exactly I was able to get the program activated. Print these instructions out and
follow them exactly. You may be using the Roxio numbers given to you as the correct numbers. Those initial numbers are only the numbers required to get to the sacred orange numbers necessary to activate. Good Luck.
Here is the post by John at Roxio:
Activation is different than registering your software and is required by Roxio for components of Easy Media Creator 9 that are supplied by third party partners.
The most common form of Activation is done automatically when using the component for the first time when your computer is connected to a live internet connection.
Auto-Activation:
1) A Product Activation window is prompted when trying to connect to the Roxio server to activate the mpeg2 component used for DVD authoring/encoding.
2) Click OK when prompted "The following code(s) must be activated before using the application - MPEG2"
3) Once activation is successful, you will receive a confirmation prompt.
If this fails, then you have to option to manually activate your product, but still requires a connection to the internet. To do so:
Manual Activation Instructions:
If this fails, then you have to option to manually activate your product, but still requires a connection to the internet.
1) Close Easy Media Creator 9.
2) Disconnect your computer from the internet. The easiest way is to turn off your modem or disconnect the cable from the back of your computer.
3) Re-launch Easy Media Creator 9 and the application that needs to be activated.
4) Activation will fail, but this time, choose to Activate Offline.
5) In the Offline Product Activation window, copy the product 25 Digit product key listed in orange. Do not close this window.
6) Turn on your modem or reconnect to the internet.
7) Go to
http://activation.roxio.com/activateme and follow the on-screen instructions. This will generate an Activation Code that you must copy.
8) Go back to the Offline Product Activation window and enter the Activation Code into the boxes.
I have Roxio Creator 9 and want to burn a dvd. When I click on Create a DVD it comes up and tells me it needs to activate MPEG2 and connects to the internet. It will not do anything. I tried the activate offline and it does not accept the digits Roxio gave me. I have the Roxio Creator 9 registered. I need some help so please help me. Thank you. 
