What happens with sessions??

[eluser]IEDani[/eluser]
Hi,
I need to use sessions in my app and I am having problems.

First of all I try to use the session library but if you use it the library generate a lot of warnings. The only way to modify it is program in the library, and it can give more troubles.

Can I disable the session system of codeIgniter? how?

So, I decided use the traditional sessions ($_SESSION['var']) but my app don´t reconize it and tell me that $_SESSION is an undefined var.

Can I use the traditional sessions? how?

Thanks you so much!
Dani