Intermittent problem with boot and ABS,Break

I have a citroen c5 HDI 2005 with intermittent problem where on dash ABS, Break, Stop, Service light illuminate. Problem 2 is on the comp it keeps bleeping and telling me the boot is open, but the boot is not. i have change the boot lock and still the same. Now the boot wont open but still says the boot is open. Car has been attached to a computer and was told ABS, Break,Stop lights is a fault with the ABS pump (2 sensors faulty)! but this problem is intermittent. And was told that the sensor in the boot is faulty, but again intermittent. Help please