I'm not familiar with your set, but some sets do not allow a zoom or stretch if you are receiving an HD signal. Try putting your 6000 in SD mode and see if your set will zoom then.
With the 6000 your screen should stay in the mode you've selected, it won't revert to 4:3 during a commercial. Keep in mind that even HD channels send out 4:3 commercials in a 16:9 window, so it appears that you are viewing 4:3 but you are really viewing 16:9.
With the 6000 your screen should stay in the mode you've selected, it won't revert to 4:3 during a commercial. Keep in mind that even HD channels send out 4:3 commercials in a 16:9 window, so it appears that you are viewing 4:3 but you are really viewing 16:9.