I had some trouble with my macbook pro going freezing while attempting to sleep after I did a hard drive upgrade and restored my files with apple’s wizard.
It turns out the problem may be related to the way the mac is put to sleep… I followed a few steps on this article and things have been quite stable since:
http://www.windley.com/archives/2007/10/fixing_macbook_pro_sleep_problems.shtml
Good luck with yours!
