Front brakes stops working abruptly

Hey guys, i have speed 400. Whenever i go in a very slow to normal speed and when there is a terrain change like tarmac to bit dusty road my front brakes goes completely hard automatically. I even ended up in a small crash when the brakes went hard. Mostly its working fine in normal roads but all of a sudden this happens and im suspecting the abs or traction usually behaves like this. Anyone faced similar issue or any suggestions pls