Is there any danger in eating frozen food which is out of date? This
may sound a silly question, but my understanding of the processes
involved is that:

Freezing prevents any bacteria from multiplying.
Cooking thoroughly kills any bacteria that might be present.

If I am right there doesn't seem to be any reason for not eating the
food, but I don't want to make people ill!

Am I missing something here that I aught to know about food poisoning?