When open an existing report, BIDS only showed a long line of codes, no actual report layout at all

 

 

It seems that the error message you have provided is a known issue in SQL Server 2008. The issue has been fixed in the latest SQL Server 2008 R2 build.

To solve the issue, please try to remove the code parts: DataType=”Integer” in your xml file, and you can follow

 

Thread: http://social.msdn.microsoft.com/Forums/en/sqlreportingservices/thread/23cb9754-be0e-435c-b2ee-820eb84646c5

#Value! Error on exported Excel file from SSRS rpt

Solution :

  Right click those troubled columns -> choose the text box properties ->  click the Number tab -> highlight number section -> check ‘ Use Regional Formatting’.

This seems to be able to fix the issue

Link: http://social.msdn.microsoft.com/forums/en-US/sqlreportingservices/thread/7aa7f32b-efd5-4f40-914c-ec62f0ee5e0c/