I have been running into problems with Office2007-generated PDF files. You can read all about it here.
TL;DR: Some PDFs generated from PPTX files using the "Save as PDF/XPS..." add-in are rendered only partially and trigger error messages in Adobe Reader/Acrobat Pro.
After trying many other options outlined in @harrymc's answer to my other question, and after confirmation from other users who have encountered the same problem, I have decided to get Microsoft support involved, which is quite expensive (€299 + taxes which you only get refunded if the support incident uncovers a bug in an MS product, and if support decides that it's in fact a bug).
My problem now is that in the first return call, MS tech support suggested that if only Adobe Reader/Acrobat are having a problem with the file, but Foxit or Chrome can render it correctly, then it's Adobe's problem, not theirs. So now it looks like I need to be able to prove that the generated PDF is in fact invalid.
In my other question, @harrymc provided an error message from GhostScript which suggests to me that there is in fact an error in the PDF. But can I really take this as evidence? Is there something like an official PDF validator that can point out exactly what's wrong with my file? Or with Adobe?
For reference, here's one file that's causing these problems.
MS tech support has been able to reproduce the problem (even in their own XPS viewer), and they agree it's a bug (although they called it a "limitation", gotta remember this), so I won't have to pay for the incident. They will pass it on to the developers, but couldn't guarantee a fix and recommended an upgrade to Office 2010. I'll have to see if my university will play along with this - our standard is currently Office 2007, but I know my license is also valid for 2010.