HDTV widescreen - Grey bars on side, not black?


I have a small (23") Sony Bravia HDTV and the bars on the side for regular 4:3 television are bright gray, not black. It's driving me crazy. I've been on the phone with Sony and they don't know if it's possible to change the bars to black, but the salesman and J&R World says there is but he doesn't know how. My cable company says it's a TV issue and Sony says it's a cable issue.

This particular TV has been discontinued so I can't find it in a store to ask a salesman.

Anybody have an idea?
kublakhan
Post removed 
Post this question under "Home Theatre" and you might get a few more responses.
Sometimes I get what Elizabeth desrcibes and if I toggle the channel up and down it goes away when I go back to channel I want to watch. My fathers TV does either black or grey bars thru units menu.
I get mostly black but some grey. I THINK that the gray is better because there actually is a signal and therefore less chance of burn-in. If I am wrong on that, someone will let me know. If you post on avsforum.com, I am sure someone will be able to help you out immediately.
Thanks for all the responses - i've checked all the settings many times on my own and with Sony tech support on the phone but there's no setting for the bars to be found.

Thanks Swamp, I posted the question on the av forum you suggested.