Reports from clients are probably piling up in the \BES Server\FillDBData\BufferDir folder. If you see a lot of files in the folder, you have a problem.
Try checking:
Is SQL running?
Cycle the BES FillDB service. (If it hangs while stopping, you may need to terminate the process.)
Ask your DBA if there are hung sessions/threads to the DB. If so, terminate them.
When the issue is resolved, it may take a while for the contents of the BES Server\FillDBData\BufferDir folder to be stuffed into the DB. (There is a chance that FllDB will become overwhelmed and hang again. If so, cycling the FillDB and/or Root Server services may be necessary.)
After your Root server is healthy, then you may need to cycle your relays if they are hung.