[opencms-dev] [newbie] impossible login after setup

[Newbeewan]

Hi,
I'm very newbie on this tool.
I build it, copy the .war to $TOMCAT_HOME/webapp/
tomcat well deploye it and I manage to run the installation process.
It finished successfully, and I've got the first wellcome page.
If I try to log in ( with Admin/admin ), it come back everytime to the 
login page !
If I refresh the wellcome page, it wrote that I'm now admin, but I can 
do nothing, because every time I retry to go to the admin panel, it 
prompt for login/pass :((
My config :
serveur : opencms5.0.1/tomcat5.0.28/j2sdk1.4.2_05/linux( kernel 2.6.7 
)/MySQL 4.0.21
Client : mozilla1.7.2/linux
Thanks a lot for your help

Mourad