When I have CCleaner checked to "Delete index.dat files", then after restart, I am not logged in into forums. When I have it unchecked, I am still logged into forums. Do not know, if it is a bug or they way like Cleaner handle index.dat, but when I was using IE 7 Beta 1, I had no problems at all. By the way, CCleaner is the best security utility I have.
EDIT: Sorry for spam, I have already found topic about it:
http://forum.ccleaner.com/index.php?showto...913&hl=IE7+Beta