Is it true that...
The way SQL Server 2012 Express works is by registering
these App_Data databases by name across your entire machine and the
names are not allowed to be duplicated. So, if you have 2 copies of
PlanetWrox in two different directories, you are almost sure to run
into this type of problem? Could be the source of some of my problems that I have been having with SQL Server 2012 lately?