Just came across this article on zdnet that claims:

"Now, while you Americans go get that bit of looniness fixed, I'll contemplate an Air Canada electronic ticket I just got that requires Acrobat Reader 6 but is hardwired not to allow font substitution -meaning that if you don't have Microsoft's Verdana fonts installed, you can't read the ticket."

I have the Verdana fonts installed, and am not about to uninstall to check... If true, I hope an AC lurker will have this brought to the attention of the IT group.