i have installed ispconfig 3 on digitalocean debian vps with 512 ram for 3moths now. everything was working well but now i cannot log into ispconfig as i get "user or password empty", also i cannot access any of my wesites on the server ( 3 joomla websites) - i get "Database connection error (2): Could not connect to MySQL." when i try to navigate them from browser. but if i restart the vps server, everything works fine for about 10 minutes then the issue strats all over again. please help.