resolution problem

Hi guys
i flashed my vu duo yesterday with open vix Zeus. everything is working ok, except when when i change channel, the picture shows great, but after a second or 2 the screen goes blank, then when picture re appears it looks as if there is little blocks of a different channel in the corners and on the side of the screen showing through.
its happens if i swich from sd to hd and visa versa.
Can anyone help please?
thanks.