Sql Server agent can not start
SQL Server Express Edition does not include SQL Agent functionality.

While the installer does register the service entry, the service will fail to start if you try. (I verified with one of my own instances -- the error message I got is exactly the same.)

See this MSDN article for a comparison of features available in each edition of SQL Server 2008 R2.

If it's appropriate for what you need to accomplish, you can use the Windows Task Scheduler instead.