Why was Crusher replaced with Pulaski who was replaced by Crusher?
In season 2 of TNG, Dr. Crusher was replaced with Dr. Pulaski. In season 3, Dr Crusher came back. The best information I can find is "On Star Trek TNG, why was Crusher replaced by Pulaski? And...?" on Yahoo Answers. But there must be better more complete information out there.
And here's a quote from a fan site -- far from reliable. http://www.enworld.org/forum/media-lounge-miscellaneous-geek-topics/39444-crusher-pulaski-crusher-switch.html
@JackBNimble: Probably due to her disrespectful attitude towards Data. You could say she was a speciest (in analogy to "racist") prick.
"after a phone call from her co-star Patrick Stewart, McFadden changed her mind" - that voice can do anything.
In universe, she was the head of Starfleet Medical.
From "The Child":
WESLEY: It's going to be hard leaving the Enterprise.
PICARD: Mixed feelings for all of us. It's always difficult leaving any ship, just as it was for your mother when she left to become head of Starfleet Medical.
When she returned, not a lot was said, but in "Evolution" it's implied that she may have returned because it was difficult to be separated from Wesley:
PICARD: If you're concerned about Wesley, I see no evidence that there's a problem.
BEVERLY: I know. In a funny kind of way...that's exactly my point. We talk. We smile. It's almost too polite.
PICARD: Beverly, this is simply a matter of time. I know how difficult it was to be away.
BEVERLY (vulnerable): Tell me about him.
Out-of-universe, then-head writer Maurice Hurley didn't like her.
According to some recent reports, there was some sort of problem between Gates McFadden and producer/writer Maurice Hurley. I've heard this characterized in some places as sexual harassment, but I'm not sure that's based on any actual allegations. Rick Berman did say he was at the center of it, though:
Gates McFadden fired at end of first season because head writer Maurice Hurley "he had a real bone to pick" with Gates and din’t [sic] like her acting, Berman brought Gates back for 3rd season after Hurley left
(That quote is from the summary here.)
This comment also cites her hair (of all things) as costing lots of time and money to keep styled right to avoid continuity problems. Not sure I buy it, but there it is.
So... Who gave the downvote? This answer is quoting one of the executive producers of TNG, and seems to explain why the other answer qualifies itself as the "official" explanation - as though this is _true_ explanation that they didn't want known at the time..
Dunno who gave any down vote, but this is one of the best explanations so far: Dispute with staff + character costs are definitely at the top of the list of reasons to write a character out of a TV series; it's all about the money at the end of the year. Maintaining McFadden's Locks for continuity most certainly incurred many $$ in retakes for the early seasons.
In S02E01 Picard says to Wesley, "Just as it was for your mother, leaving to *head Starfleet Medical*." (so it's canon)