Outlook 2010.
When certain users, not all, get meeting invitations, they open the email and have the "No response required" in the field where there would normally be "Accept, Decline, Tentative" buttons.
I dont think there is any relation to screen size, add-ins, hot fixes, or other posts I've seen.
There has to be a way to modify the reading pain when it comes to calendar invites.
I've tried with Office 2007 and 2010 and on different machines with one particular user and they still have this issue.
Tried in both cached and non cached mode, repaired, etc...