SQL Server 2008 error when changing the number of cores I have a virtual machine (virtualbox) with Windows Server 2003 and SQL Server 2008, running with 4 cores. I wanted to use 6 cores, but when I changed the machine configuration, for some reason SQL Server stopped working. I couldn't start the service - it was giving me an unhandled exception without any extra data. 

Does anyone know a fix for that? I can live with 4 cores, but I really want to upgrade to 6.

(I know is this setting, because as soon i went back to 4 cores SQL Server started to work again)

I think there has to be a way to upgrade the machine without reinstalling.
Check the version of SQL Server. Enterprise version may be required.