Had a similar issue when trying to open PDFs. Called DataViz TS and they advised that sometimes a document is not compatible because of the the differing formats in which it could be created. If the PDF was created as an image, it will not open. Tried a different document and it opened fine.
Call TS at: 203-874-0085 or check their Knowledge Base. Your situation may be similar.
I ran into the same problem but realized I had been able to open one small Powerpoint presentation. Turned out that was one I had created earlier today, in .pptx format, unlike the others I was trying to load with .ppt format from earlier work. I just converted a very large .ppt file to .pptx and my blackberry tour reads it just fine.
I ended up going to the PPT viewer and on the BB menu there was an option for "check for updates"
It directed me to the developer’s website. From there I did an upgrade to the new version. (mine wasn't as easy as you would think though. had to delete the old version which took some time, reboot, then go back browser history and downloaded new version)