If I remember correctly when creating an option gruop you're given the option of selecting a default button. If you don't select a default button, all boxes will be left unchecked.
An alternative would be to create one more button than you need, select this as the default, and set it's Visible Property to "No"
Hope this helps.
The Missinglinq
"It's got to be the going,
not the getting there that's good!"
-Harry Chapin