The problem:
When i am logged in as admin, my plugins using jquery don't work e.g. quick chat, lightbox plus, and even wp-filebase download tree. Only guests and regular members remain unaffected.
When i disable wp-filebase, everything works fine.
After speaking to the wp-filebase author, Fabian, he discovered that
By removing the jquery-ui-tab dependency, it fixed the problem. But could not find the reason why this has been causing trouble.
My site site loads the jQuery scripts from the google AJAX service, not from the local wordpress version, maybe thats the cause.
Any ideas ?