Switching to the final version of the acm siggraph latex template always messes up the first page, but lately I've had a lot of trouble with the copyright space. Somehow I end up with blank space all other the first two columns rather than just a small portion at the bottom of the first column. To fix this, in acmsiggraph.cls I replaced:
\footnotetext[0]{\rule[\ACMcopyrightspace]{2.71828in}{0in}}%
with
\footnotetext[0]{\vspace*{1in}}%