Advanced Search in PCUI doesn't open

Hello,

when I press "Open Advanced Search" in PCUI in our CRM development system advanced search GUI does not open.

This behaviour can be watched in any Business Objects as Accounts, Contacts, Opp, Leads,...

Restart of dev portal didn't help. There is no error message in browser nor any system dump available (st22). Simple Search works well.

Any ideas where I could start to find a solution (where to focus debugging)?

Best regards

Robert