Problems trying to create a rollover button

I am having troubles trying to create a rollover button. I am following a tuturial where after I create one button I switch to Image ready and then click on the rollover state button. I then drag the first button layer to the new layer icon to create a duplicate and then edit this buttons properties for the rollover. However I have noticed that when I preview the rollover in my browser the rollover effect is enabled as soon as I move my mouse into the browser window instead of once I move my mouse over the button.

Anyone know how to fix this?

Also can someone point me to a good tutorial on creating rollover navbuttons? Ive tried to follow one or two and have ended up totally lost.

Thanks.

Does your button have a slice??? The slice tool can help you select an area where your button should be aware. if you're using photoshop 7.0 try using the layer-base rollover button found beside the create new rollover button