Type 'System.String' cannot be marshaled as an unmanaged structure; ... error is back

Question

The error discussed in this post http://scn.sap.com/thread/1890650 seems to have crept back into SP12.  The following code:
Using dbConnection As SqlConnection = GetNewSQLConnection()
                    .AddLoginInfo(dbConnection)
                    If TypeOf .Report Is IHasParameters Then
                        DirectCast(.Report, IHasParameters).ApplyParameterValues()
                    End If
                   If .Report.Rows.Count > 0 Then
                        .PrintToPrinter(.PrinterPageSettings.PrinterSettings.Copies, False, _
                                        .PrinterPageSettings.PrinterSettings.FromPage, _
                                        .PrinterPageSettings.PrinterSettings.ToPage)
Gives the error at If .Report.Rows.Count > 0
Type 'System.String' cannot be marshaled as an unmanaged structure; no meaningful size or offset can be computed.
The report does contain a blob - I tried deleting it and dragging it from the table - again, but the same error appears before and after.  The type of the Field object is IFieldBlob.  Oddly enough, other reports that also contain this field, currently seem to be working, although we will have to revisit all of them now.
I am using VS2010 and SQL Server 2005.
Any help would be appreciated. 

Answer 1

Partial work-around:
    ''' <summary>
    ''' This function is a workaround of the Crystal Reports bug that causes a report with an image in it
    ''' to fail when the report is checked if it has data.
    ''' </summary>
    ''' <param name="Report">Report to check</param>
    ''' <returns>Number of rows in the report</returns>
    ''' <remarks>If the check throws an exception a value of one will be returned.</remarks>
    Friend Function GetReportRowsCount(Report As ReportClass) As Integer
        Try
            Return Report.Rows.Count
        Catch ex As Exception
            My.Application.Log.WriteException(ex, TraceEventType.Warning, "GetReportRowsCount for " & Report.Name)
            Return 1
        End Try
    End Function
I use this function in place of the check for Report.Rows.Count,
This allows most of my reports to work correctly, but allows the odd blank report with an image on it to print.  Oddly enough, some of the older reports with logo's on them seem to work correctly.  The newer ones run into this problem.
Neil