"Problem Saving PowerPivot document"

[kcmuppet]

Anybody got any ideas how can I work out how to fix this problem?

The error message below is popping up:

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Error Message:
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Value does not fall within the expected range.
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Error occurred while setting the Sandbox Table Count.
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Call Stack:
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at Microsoft.Office.Core.CustomXMLPartsClass.Add(String XML, Object SchemaCollection)
at Microsoft.Office.PowerPivot.ExcelAddIn.ExcelInterOpUtil.SetSerializedContentAction(String content, Workbook localWorkbook, String key)
at Microsoft.Office.PowerPivot.ExcelAddIn.AddIn.SetSandboxTableCount(Workbook wb)
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at Microsoft.Office.PowerPivot.ExcelAddIn.AddIn.SetSandboxTableCount(Workbook wb)
at Microsoft.Office.PowerPivot.ExcelAddIn.AddIn.Application_WorkbookBeforeSave(Workbook Wb, Boolean SaveAsUI, Boolean& Cancel)
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Cross posted here