APEX integrated with SSO sometimes goes into Infinite Loop on login
We've integrated an APEX instance with Oracle SSO, successfully. Users are able to login with no issues most of the time. Every now and then, someone will have a problem where they
1) Navigate to APEX (http://myserver:8080/apex/f?p=400:1)
2) Click the Login link
3) Get Redirected to the SSO login page
4) Login successfully in the SSO login page
5) Get redirected back to APEX which immediately redirects back to SSO which immediately redirects back to APEX...
We've tried clearing cache, switching browsers (IE 8.0.7600.16485, Firefox 3.6.17, Chrome 11.0.696.68), rebooting. Nothing we do fixes it, but then it usually straightens itself out within a day or two. So every time I've opened an SR, it's no longer a problem by the time I get an analyst to look at it.
I've completely run out of ideas on how to troubleshoot this and was hoping someone might have an idea of what else I can look at.