That seems odd. Never had that happen before.
When you say it recently happened, do you mean a few hours ago or a few days ago? Have you tried closing Max and restarting?
Is it possible that maybe you changed the default Position Controller?
Select any object
Go to the Command Panel > Motion Tab
Expand the "Assign Controller" rollout
Expand the object’s "Transform: Position" and click on the one for Position to highlight it
Click the "Assign Controller" button
Check the list and make sure “Position XYZ” is selected. If it's not, click it and then click the "Make Default" button