Just got home in my 2wd saff as i pulled up the brake pedal went solid and i had very little braking effort, i lifted the bonnet and there was a buzzing/clicking noise from the black canister near the servo.
switched the car off left it five mins then took it round the block and its fine. has anyone delt with anything like this before?

 

anyone? been out in the car a couple of times since and it seems fine, just a bit concerned it might do it again but when im giving it some

 

sounds like the ABS pump was running continuously and over pressurising the system..
Check the condition of the connectors and their contacts around the brake master cylinder and pump, especially the 7-pin one on the pressure switch, it is this switch that turns the pump off when the system reaches working pressure, via a relay, and if it isnot making good contact it can allow the pump to overrun.
I've had this once myself, but never did it again to absolutely trace the fault, But I think this was the reason.