I have done like this for generating pdf at runtime when i click on the print button The process is like this when I click on the print button the pdf is generated with fol
Extract from http://pdfsharp.codeplex.com/releases/view/37054:
If you favor speed: stay with PDFsharp 1.30. If you favor small PDF files: use PDFsharp 1.31. Future versions of PDFsharp will support both modes (favour speed and favour size).
Maybe this helps.
Enable exceptions handling in VS like here and you will gotten exact exception description. Looking on your problem description sounds like this could be rows quantity limit. By the way check out the link.
Regards.