I just recently upgraded from SQL Server 2005 standard to SQL Server 2008 R2 Enterprise. After I install was done it said something about "MSSQLDBDefaultUser" which was created some time ago didn't exit. Looking at Active Directory this user does exist and is active. <o:p></o:p>
So I let the install finish and noticed that some of the services were not started so I went in and restarted them. All of them restarted except for the SQL Server Agent service. It came back saying it couldn't start. Error 2: The system cannot find the file specified.<o:p></o:p>