This seems solved now. I went to this folder:
C:\Program Files\Microsoft SQL Server\MSAS10_50.MSSQLSERVER\OLAP\Data\MediaConsumptionAS.0.db
and deleted this file Consumer.6.dim.xml
that was pointed to by one of the error messages. I also verified that this file had the error text "Internal error... bla.. bla... (se thmy post) inside.