shifting option buttons
 

I have created a questionnaire made up of cells for entering answers and
option buttons in Excel 2007. I have protected the sheet and locked all the
cells except the cells that are available for entering answers to the
questions. Everything is working great except when a user is filling in the
answers and tabs through the sheet the option buttons appear to shift and
duplicate in a wierd way. If you click move around on the sheet , the option
buttons eventually correct themselves. I have the properties set to "don't
more or size with cells" for all the option buttons and I have the option
buttons in group boxes. The option buttons don't permanently, physically move
but they sort of blur and duplicate?! How can I stop this?