I know the must have/must had thing has been asked before but I have yet to see it in the context of this question.
Does "have" make grammatical sense in the following? It sounds like it conflicts with the "at that point in time."
"I remember clearly my seventh birthday (and my subsequent trip to the hospital). At that point in time, I must have been told a thousand times not to stick things in the toaster."
The main problem I'm having in my head is that if you take out the "must" then it would be grammatically correct to say "At that point in time, I had been told a thousand times..." Yet once you put the "must" in, it seems incorrect to use "had." This is my main question.