Error when using PowerPivot workbook as a data source: "XML parsing failed at line 1, column 1: Incorrect document syntax"

You may see the following error when using Excel to make a data connection to a PowerPivot workbook, or during a scheduled refresh of a PowerPivot workbook that uses another PowerPivot workbook as a data source on SharePoint 2010:

XML parsing failed at line 1, column1: Incorrect document syntax

This could be caused by a Service Pack update to SharePoint 2010. To resolve the issue, reinstall the SQL 2012 version of the MSOLAP data provider (MSOLAP.5) by following the instructions in this article:

http://msdn.microsoft.com/en-us/library/ee210608.aspx