Unable to logon as SAP*

We have restored a copy of our EP 6.0 production portal to a DR(Disaster recovery) site. This was from an offline backup. We are on J2EE 6.20. After restore and restarting the J2EE server, the logon page comes up fine but does not allow any logons. We activated SAP* and still cannot logon as SAP*. No error message appears. It reverts to a blank logon page. Please advise on what might be happening and what may be the fix?

Thanks