BI 4 - Web intelligence blank page from BI Launchpad

Hi

We've just migrated from BO XI 3.1 SP 6 to BI 4.1 SP 6.

Users are authentifed on a portal from which they reach BI launchpad. When they try to open an existing report or when they click on "Web Intelligence" link, a new page is opened but it's blank. This issue occurs for some users, but not all of them and it doesn't when users connect to BI launchpad "directly" (without portal).

After reading some discussions here about "blank pages", we tried to clear tomcat cace and redeploy webapps too, but the problem remains.

Where this problem can come from ?

We see no message in log files (yet we started tomcat with "debug" logging level) ; how is it possible to get more logs ?

Thanks