You didn't have your finger on the Shift key by any chance on startup? That disables login items.
This article describes where the plist is for login items and some ideas for managing them.
QUOTE
It is stored in a preferences (.plist) file called loginwindow.plist, located in the ~/Library/Preferences folder (i.e., in your Home directory). Note: This is a separate file from the com.apple.loginwindow.plist file, also in the same folder.
http://www.macfixit.com/article.php?story=2005091208251414