Hello, I think that you have a dangerous situation there and get the POCO to do some step potential tests within the area where the cable is buried.
It is possible that the cable screen earth has failed and leakage of the cable insulation causes above mentioned problems.
There may not be enough fault current to trip the main breaker or High Tension fuse.
Contact the POCO rather sooner then later, and try to get a photo or video from the effect seen in the grass.
Keep us posted what happens.
Last edited by RODALCO; 12/07/12 10:42 PM. Reason: typo error