Well damn...
...the change I posted shouldn't have affected page display. All it changes is how the system generates/stores cookies.
Did you make both changes? include/class.ostsession.php and main.inc.php?
Also, I guess something else to check would be if you have cookies disabled in your browser.
Ok, well i don't understand why but your solution helps even if it was not the real one
i made the changes in both files, even if in the main.inc.php, i don't have the part of code they show
In all case, to restore the file, i replace my class.ostsession.php by the original from the zip, and now it works -_-'
I don't know why ! maybe during the installation it change a bad parameter in the file ...
I will try now the rest of this apps :)
Thanks for your help