[otrs] SessionID is invalid!!

Hi All, I’m new to OTRS and after configured all e-mails notifications and start using and testing, I started to get “SessionID is invalid!!” message after trying to login. Now I can’t login with any of the users I have. The URL http://myipaddress/otrs/index.pl?dummy <http://myipaddress/otrs/index.pl?dummy&SessionID=&Session=10d181d5b55f2ec7e d680d35c49740ee4b> &SessionID=&Session=10d181d5b55f2ec7ed680d35c49740ee4b is returned after the login attempt. Thanks for your help, Jorge