This will most likely be due to your Room becoming overloaded with pages.
To explain, once you have reached 250 pages the Room will become overloaded (and sometimes turn red). Consequently, we always advise to keep your Notebook below 100 pages to avoid these issues which is why lots of error messages would have popped up for you. To keep your Notebook pages down and avoid this going forwards, we recommend exporting the Notebook at the end of every lesson if you can by clicking on the right hand envelope. This will clear the Notebook and send the saved work as a PDF link in an email to all participants present in the Room.
How to export your Notebook:
To fix your Room, please email firstname.lastname@example.org with your Room link. We can then quickly reset it for you.