Ok, It seems to have some kind of issue with this last version of crystal reports withe VS2010.
Is you are using Crystal Reports 13 with SP4 and Visual Studio 2010 and you have an RPT with subreports, if you try to export it by code or by the viewer to EXCEL (XLS), your application will generate a runtime error and close. If you export to Excel data only, there's no problem what so ever.
This issue is already reported to SAP Support.
http://scn.sap.com/thread/3210737
Hope it helps you.
Regards.