Radio button display problem

I am creating a math quiz using CS3 and action script 3 and Flash 9. Please see the attached screen shot. The radio buttons are supposed to be aligned with the circles in the columns. The student enters a number in the boxes at the top of each column and then clicks in a circle corresponding to the number in that column.

I have tried the quiz on many operating systems and it works fine but have found this display problem on a computer running Vista home basic. The problem was also seen at our local library running XP. All computers have flash 9 installed.

Can anyone offer any idea why the radio buttons do not display properly? Thanks for any help.

I think its because of the flash player.Try using Latest version of flash player,Install ActiveX compoent and Plugin for Flas player 9.

Thanks for your input. I will try what you suggested.