Markup issue...

We have just gone through a WF3 to WF4 upgrade and a 8.0 to 9.1 Windchill upgrade. I now have a small set of users that are having problems viewing markup notes and marks. My first thought is that it was a graphics card issue. There cards are not listed as supported on WF4 list but they are on WF5. They also worked on WF3. I have no problem viewing the markups. Has anyone had viewing issues with markups before. We do not use productview here so that is not an option.