I'm sorry, I should have said it in the post ...
I was using the browsershots.org site and the screenshots I attached have the browser info in the name ...
Specifically, (the one my client uses!) Firefox 3.0 and earlier (3.1 and higher work as expected).
Surprisingly, IE doesn't cause issues (even older versions)
Navigator seems to cause problems
Opera and Safari seem okay
and the less common browsers (that I understand are built on some of the same code as FireFox like Flock and Seamonkey cause issues