UPDATE:
I continued to research the issue and the original line of code mentioned above is not what acutally caused the crash. I kept commenting out blocks of code until I finally got things working in the Release build and then start adding back until it failed again.
Here is what is really happening:
FlexCelPdfExport pdf = new FlexCelPdfExport(xls,true);
pdf.Export(reportPDFName);
pdf.Dispose();
xls = null;
The 3 lines of code above dealing with the FlexCelPdfExport are the trouble spots. If I comment out those 3 lines, it works in release mode.
So, I am thinking there is something going on with PDF export in Release builds.
Bo