[xwiki-users] Severe problem in authentication

I've the same problem of Rustedt Florian. I've install xwiki 1.2.1 (and then 1.2.2) on Tomcat 5.5.26 with JDK 1.5.0_14 in a Red Hat 4.u4 x86 Enterprise. The authentication is basically working, if i try to log with a wrong user name or a wrong password, I get an error message. If I log in with superadmin user or another valid user, I get the xwiki homepage but the user was't authenticated. In the logs i get nothing more than: !remember-me cookie validation hash mismatch! !remember-me cookie has been tampered with! !remember-me cookie is being deleted! The same xwiki version was installed on a Windows XP (with the same jdk and tomcat version) without any problem. I try to configure the parameter xwiki.authentication.useip=false but it doesn't work. Please help me! Thanks