Forum

For the 1st SS:
Search the forums. There's been numerous thread about pink PBSS.
It's a problem with PunkBuster and Windows 8 compatibility. If you google it, you will find that AA is not the only game this happens to.

For the 2nd, I do believe that's perfectly normal. I believe PB just takes a picture of a random part of your screen (I would guess it's this way because this takes up less resources, causing less noticeable performance problems while taking the shot and takes less bandwidth from the game, leaving the ping and/or packet loss virtually untouched).
I believe most (if not all) PBSS's are in fact a part and of the screen and not the whole. Over time PB takes more shots and if somebody's cheating (and doesn't use some PBSS cleaner or whatever) one of them will show it.

I'm no expert, but this is what I believe to be the truth.

You should also consider that Punkbuster itself is not flawless, and that it relies on the graphic adapter (ideally your graphic card). Under some circumstances it can't take a screen, or either the screenshot is corrupted or parts of it show wierd colours (some old Intel and Sis integrated chips are really awful).