Are component primitives locked?
Yep.
Did you select by filter, so that the pads were part of the selection as well, not just the components?
Nope. Just dragged a window over it.
<sarcasm> I don't know what you're talking about, those diodes look perfectly fine... you sure do use a lot of diodes though...
</sarcasm>
That was actually my first tought too: geez, how many diodes did they put there!

Altium threw a tantrum around that time (ie 786 523 889 error boxes, rats nest screwed up,...) so I guess it was just a more interesting way for Altium to crash. Still sucks though...