Problem with Vokera UNICA HE?

HI
I have the Vokera UNICA HE Condensing Boiler.
For 2 yrs the boiler has worked fine until yesterday when i came in from work and there was no Pressure in the boiler. I topped it up and away it went untill about 2hrs later and it again lost all Pressure. I had already checked the Rads and found no problems (Leaks etc) so i again topped the boiler up. This time though the boiler was swiched Off and Cold. I got near to 1Bar and started hearing Water running down the Condensing Pipe which i thought was unusual because i thought that should only have water running down when boiler is working!!

Could that be the reason im loosing Pressure???. I dont want to start ripping up carpets checking pipework if this could be the reason for loosing the Pressure...

Any Ideas or answers would be fantastic

Regards

Dan