The fastest resolution may be to reload the OS from scratch, wiping the hard drive first to be sure, but that doesn't offer any learning experience of what happened and why.
My guess is when it shut down that previous night, something got corrupted that now when you login it initiates the logoff action.
This could be a corrupted policy, errors in the registry, a bad file pointed to by the HKEY CURRENT USER area of the registry, a bad file in the startup file folder for the users, a permission error.
A couple of things to try,
1. Install a tool like ccleaner and disable allot of the startup items to see deactivating some piece of global software allows the other logins to work
2. Clean out the temp files under the user codes that don't work
3. Change the user codes that don't work to give them administrator rights and see if the login works then
4. Check out this result from a google search http://www.vistax64.com/general-discussion/221912-standard-user-account-just-logs-off.html
http://support.microsoft.com/kb/555648
Dave