Specifically, software such as CCleaner, which deletes temporary/junk files, and internet security software, which deleted files to protect your privacy. If Internet Explorer is not set to delete it upon the end of a session (an advanced option), that is the next place to look.
I am currently running Vista Business fully updated with IE8. I have saved logins for a few websites like Hotmail and a couple of others. Everytime I shut down the computer and then restart I have to retype my login info. I have unchecked everything in Saftey...Delete Browsing History except Preserve Favorites Wesites Data. What else can I do to not have to keep loging into these sites.