[support] Login issues

[Daniel Carrera]

Hello,

I have a Drupal 4.7 website (I think it's 4.7) and some of my users are 
experiencing login problems. "Alice" will log in and end up inside 
"Bob"'s account. Alice can see Bob's account details, edit his blog, 
etc. Alice is 100% logged in as Bob.

Alice and Bob are in the same building, probably behind a firewall.

Does anyone know what could cause this problem? My first guess is that 
they are using a shared computer and Bob forgot to log out, but I'm not 
sure that this is true (btw, this is a school, Alice is a student and 
Bob a teacher, and Bob is not happy that his students can use his account).

How does Drupal store login information? Does it use a cookie? Or does 
it use the IP address? I have every reason to believe that Alice and Bob 
would show up as the same IP, so I hope that's not what Drupal uses. If 
Drupal only uses cookies, then that means that Bob didn't log out, 
right? Or is there another possibility?

Thanks for the help.

Cheers,
Daniel.