I'm just guessing on this one. When you choose another planet after going to the Moon, do you hit ENTER before hitting GoTo, so that the planet's name is on the top line of the display? If you don't hit enter, then the ETX computer thinks you're still trying to point at the Moon and makes a little noise while basically going nowhere.
Also, do you have your scope set for astronomical objects rather than terrestrial? Are you sure you have it in the mounting mode (altazimuth or polar, whichever you actually use)?
If the above suggestions don't pan out, try Weasner's ETX web site at
http://www.weasner.com/etx/
or search for a Yahoo support group for the ETX scopes--most of the Meade scopes have rather large support groups on Yahoo.