Unable to log in.
Unable to access the authentication database
message when trying to log in to TheBetEngine, then this would suggest that there is a temporary network issue and or a temporary issue with the data centre that houses TheBetEngine authentication servers.
These problems tend to be transient, so if you get the error, try leaving it a few minutes and trying again.
If you get the message repeatedly, then please try rebooting your router and then your PC.
If the rebooting operation does not fix the issue, then you can employ a workaround to get back online:
Try logging in again, but this time hold down the CTRL key whilst you click on the Login button (and keep holding it down until the "Loading Betting Systems" message appears)
Note - this will disable all remote (non-Betfair) functions but should allow the log in to proceed.