I recently tried to open and edit the Sales Performance Dashboard. I got the message “Cannot Edit Dashboard. The dashboard could not be opened. Maximum no. of columns allowed in the layout is 4.” I also tried to make an unmanaged copy of the dashboard with no success, as I got the same error message when trying to open this one as well.
I have found that this is a bug in Microsoft Dynamics CRM 2011 and 2013 that back in 2011 was promised to be fixed in the release of 2013, however has not been. Please refer to KB Article at the following address: http://support.microsoft.com/kb/2503843/en-us?sd=rss&spid=15707
Hopefully this will be resolved in the future, however it still seems to be an issue in CRM 2013.