When I go to the Properties tab, click on Object Modifiers, and then Add Modifier, I notice that a lot of the modifiers are missing. For example, "Mask" modifier does not appear, "Boolean" also doesn't appear, and neither do several others (which would take a while to label). I'm using blender 2.76b, but I was also missing them in 2.74 (which I was using before 2.76b).
any ideas on what it could be?