Button problem

Hi there,

I have put together a flash nav bar for a client.

It can be viewed here:
http://www.castleross.ie/

My problem is that the buttons can often be unresponsive. Sometimes you have to click 2 or 3 times for the button to work. I am completely stumped as to how to fix this. Can somebody help please?

The flash file can be downloaded here:
http://www.castleross.ie/homepage.fla

Thank you in advance.

Ross