Problem Uploading ALL slides in a Presentation

Hello,

I have PowerPoint 2007 and I save my slideshows as PDF files before uploading them. Often times I upload a 50-80 slide presentation and only the first 2 or 3 slides is visible. What am I doing wrong?

I tried downloading the Office 2007 plug in but my fonts and some of my graphics don't convert properly so I prefer the PDF File upload method.

Thanks.