When loading an InfoPath form from an intranet/Sharepoint etc, the form template is downloaded and cached locally. Sometimes after the template has been upgraded on the server the local client doesn’t always get the upgraded form template but uses the local cached copy instead.
You can rectify this by clearing the local cache;
Infopath /cache clearall
Verify that the cache has been cleared by navigating to the following folder for XP+
C:\Documents and Settings\[User]\Local Settings\Application Data\Microsoft\InfoPath\FormCache2
Or for Vista;
C:\Users\[User]\AppData\Local\Microsoft\InfoPath\FormCache2
Underneath the FormCache2 folder there will be a folder with a GUID name, check inside here, it should be empty, apart from a file called _SCVer.dat.
platinumdogs.me 
This apparently has to do with the template upgrade policy and the user not having local administrator permissions. Sometimes the users still need the old version. What to do then?
Infopath /cache clearall did the trick for me, thank you.
DxIUT6 Excellent article, I will take note. Many thanks for the story!
sorry, where do we run the infopath /cache clearall command? DOS? I get a bad command or filename.