This library was written by necessity after we (my development team) found a major bug with Internet Explorer (all versions). It does not like the cookie set by the session library that comes with CI, or any of the other libraries we tried.
So, we created a new library that uses native PHP sessions to manage the session itself, but uses the database to store the session data.
It is working for CI 1.7.1. It’s a drop in replacement, all standard session methods work as intended. Just save this code in /system/application/libraries/Session.php
[EDIT by mradlmaier]
It seems to work with CI 1.7.0, too.
[/EDIT]
Hope this helps anyone having the same problems we did.