WAYLAID: Britain's Queen Mother Elizabeth, who will turn 101 on Saturday, withdrew from a public engagement scheduled for Wednesday, owing to high temperatures at home. Her doctors, saying that she is suffering from mild heat exhaustion, are waiting to see if she recovers sufficiently to take part in birthday celebrations slated for this weekend. "She's fine and up and about," William Tallon, the Queen Mother's long-serving steward, told reporters outside her Clarence House residence. "People shouldn't worry" . . . DENIED: R.E.M. guitarist Peter Buck, 44, in a British court on Tuesday, pleaded not guilty to five charges relating to an alleged air rage incident on an April 21 British Airways flight from Seattle to London. The American musician has had a trial set for Nov. 12 . . . HALTED: The northern California rock group Smash Mouth has canceled immediate tour dates after the death of its lead singer's infant son, Presley Scott Harwell, son of Steve Harwell and Michelle Laroque. The child (born Jan. 26) died Saturday of complications from acute lymphatic leukemia, a rep told the Associated Press. The group, which performs the old Monkees's hit "I'm a Believer" at the finale of the movie "Shrek," does not know when it will resume its schedule . . . DIED: Marjorie Burke, 106, possibly one of the nation's oldest voters (if not THE oldest), died in upstate New York on Saturday. A special-education teacher who earned her education credential even before the 19th Amendment (which gave women the right to vote) was put into effect in 1920, the staunch Republican cast her ballot in every presidential race from Warren G. Harding's to George W. Bush's, said a surviving nephew. Once, however, she threw her vote to a Democrat: Franklin Roosevelt, in her desire that he'd pull the country out of the Great Depression.