The latest version of MacBook and MacBook Pro are affected by several glitches, according to users, especially when playing videos and scrolling web-pages.
According to some the problem is resolved by the 10.5.3 version of Mac OS X, but the patch is still on development.
Apple is trying to respond to the problem: “Apple has received reports similar to the behavior described and we are investigating those reports. Further information will come in the form of a Knowledge Base article, Software Update, or Software Release.”
Apple’s comment on a forum: http://discussions.apple.com/thread.jspa?threadID=1423733