The first release of new tool is not perfect, even if it has been extensively tested during the alpha and beta stages. This happens to each product, even if it is built by great developers.
There is an interesting discussion about this on forrst: <a href="http://forrst.com/posts/Dont_Upgrade_to_Mac_OS_Lion_Not_yet-Ido" rel="nofollow">http://forrst.com/posts/Dont_Upgrade_to_Mac_OS_Lion_Not_yet-...</a>