i am having the same problem, the report is working fine on development server and throws following exception on production server :

 

CrystalReportFormatter Error in exporting file J:\GEF\GSL\ReportFramework\Outbox\ROA_Summary.xls and error is CrystalDecisions.CrystalReports.Engine.LogOnException: Logon failed.
Details: Could not open the field definition file 'C:\WINDOWS\TEMP\roa.ttx'.
Error in File C:\WINDOWS\TEMP\{40EE75E2-EC55-4A25-B633-139885D769D8}.rpt:
Unable to connect: incorrect log on parameters. ---> System.Runtime.InteropServices.COMException (0x8004100F): Logon failed.
Details: Could not open the field definition file 'C:\WINDOWS\TEMP\roa.ttx'.
Error in File C:\WINDOWS\TEMP\{40EE75E2-EC55-4A25-B633-139885D769D8}.rpt:
Unable to connect: incorrect log on parameters.
   at CrystalDecisions.ReportAppServer.Controllers.ReportSourceClass.Export(ExportOptions pExportOptions, RequestContext pRequestContext)
   at CrystalDecisions.ReportSource.EromReportSourceBase.ExportToStream(ExportRequestContext reqContext)
   --- End of inner exception stack trace ---
   at CrystalDecisions.ReportAppServer.ConvertDotNetToErom.ThrowDotNetException(Exception e)
   at CrystalDecisions.ReportSource.EromReportSourceBase.ExportToStream(ExportRequestContext reqContext)
   at CrystalDecisions.CrystalReports.Engine.FormatEngine.ExportToStream(ExportRequestContext reqContext)
   at CrystalDecisions.CrystalReports.Engine.FormatEngine.Export(ExportRequestContext reqContext)
   at CrystalDecisions.CrystalReports.Engine.FormatEngine.Export()
   at CrystalDecisions.CrystalReports.Engine.ReportDocument.Export()