Error Line number 662 library/session.php

[eluser]pistolPete[/eluser]
You didn't answer all of my questions:

Which CI version are you using?
Do you have white spaces at the end of your controllers?

Try omitting the closing ?> tag!

Read through these treads:
- http://ellislab.com/forums/viewthread/45181/
- http://ellislab.com/forums/viewthread/69280/

Does the error occur when you call any function of your welcome controller or ist it function specific?

In the error message the session class is mentioned, but you are not using it in your controller, did you load it somewhere else?