'04 TDI 130.. brake pedal sank to the floor..

[Evil]

Since we bought the car a couple of months ago the brakes have been some of the best I've ever had on a car.

This evening the pedal (with some resistance) sank almost to the floor, a re-pump and it's almost business as usual, couple more pumps and there's nothing (like extreme brake fade is the only way I can describe it)..

Pads and discs are good, fluid level is fine (hasn't dropped), fluid is not murky, no work has been done on the brakes.
Handbrake is spot on.

Done some googling but this seems to happen after some work is done on them... not the case here..

Any ideas??

93/93