My Windows XP Home boots up to the user list screen, but when I try to log on any of the users, it starts the login but then quickly reverts back to the user list screen. Can you help?
Try booting into the user accounts in Safe Mode, or while holding down the Shift key after entering your logon information. It sounds like something running at startup isn't working properly and causing a failure. This might be malware- or virus-related, or an application failure. After startup, click Start --> Run and type
msconfig in the command window. Click the Tab marked Startup to view what applications or process are set to run when your system boots.