I dont know whether you have encountered this, but if you have logged into Oracle as different users on different tabs of the same window in IE7, the session of the previous user is getting lost.

Is this a known bug? Any workarounds?
I wanted to check with you before raising in SR with Oracle.

Have you checked the certify matrix in Metalink to see if IE7 is actually supported with EBS?

We have encountered some issues here at NHS in using IE7 with EBS, but not the multi-tab issue - this has not been tried

I do know that with IE6 I can run multiple connections to different environments, however they share the same login screen instance of IE