Baxi combi boiler over filled now dripping?

I have a baxi combi boiler problem.

The hot water stopped this morning so I looked at the boiler and the pressure was zero, so I filled it up with the water valve/tap to 1.5 pressure, but did it without the boiler on. I realised that the pilot light was out and rebooted the boiler but the pressure shot up to over 3! Which I know isn't good

The hot water is now working, but there is a small drip of water constantly coming out of the bottom of the boiler and an L5 flashing on the LCD screen, any ideas what this might be and is it dangerous?

thanks

maria
March 2009