If you renamed your PC, was it before or after the SQL Server was installed?  You may also need to do a sp_dropserver 'oldname' and an sp_addserver 'newname', 'local' to get the name resolved.

You can see if it is the wrong one if you use sp_helpserver or select * from sys.servers and look at the name.  If it is not the same name as your PC has, then you need to change it like above.

EXEC sp_dropserver 'oldname'
EXEC sp_addserver 'newname', 'local'