95 740i audio wierdness

[cackman]

help,someone,please
my 95 740i electrics have gone mental
when driving along with the radio on,suddenly the display changes to the menu page,then the "telephone" listing blacks out,followed by the computer,then everything else,then after a couple of minutes,the audio cuts out.when this happens,all controls on the head unit lock up.
at the same time,my indicators work,but dont show on the dash,same with the full beam.this continues until i brake down to about 5mph,when my indicators & full beam then show,and if i hit the power knob on the head unit,the audio returns,though only temporarily,tough all lists on the menu page are still blacked out.im pretty sure that this must be a loose conection,but must admit to being stumped as to where to look.
any ideas???