Read original post by Geert van der Cruijsen at vdcruijsen.net
The free apps I had in the marketplace were running Google’s Admob as adprovider because when I wrote the apps Microsoft Pubcenter wasn’t available in the Netherlands yet. When I was upgrading my Apps to Mango I found out that version 4.0.4 that is currently the latest release of the Windows Phone Admob SDK is broken will always give you exceptions when you include this control. Seeing Google wasn’t to keen on fixing this since it was mentioned a lot in admob sdk Google groups I decided to switch to Microsoft Pubcenter because it came available for Dutch people.