Asset browser

Hi there D5 team. I just started using D5 5 months ago. So far, so good and I like the convincing results especially for exterior scenes. I have been having a problem lately: Right in the middle of a project, the asset browser gets disabled: I cannot select or edit materials because it gets disabled. What is the problem? What am I not doing right?
Thank you.

Hello, sorry for the inconvenience, could you please show me a screenshot or some details?
How it got disabled?