BI Launchpad Internet Explorer 9 issue

Hello,

I have an issue using BI Launchpad and Internet Explorer 9.0.

System is up-to-date (BI 4.0 SP6). We are coming SP4 - where we didn't have these problems. We configured SSO which is and was working.

Some users aren't able to login via BI Launchpad, they'll receive following screen. They should be logged in automatically (SSO) but instead they'll see following broken screen via Internet Explorer 9:

The same happens if I try to use the BI Launchpad with an user which is not available in BI and Internet Explorer 9. If I use Chrome instead of Internet Explorer, I'll get following screen - which is correct:

Any ideas or anyone having the same issues? I stopped / re-startet servers and the whole system.

Thanks!!!

Christian