I've only had my XFire a few days but it appears the rear drivers sub speaker is vibrating. But, it only does this when it is cold. When it is warn the vibration goes away. The problem is by the time I get to the dealer to get them to look at it, it is all working fine as it has warmed up. I took the cover and carpet up and checked the screws to ensure it was tightly fitted and it was, yet it continues to vibrate. Is this a duff speaker or is it actually something else that is vibrating?

It is really frustrating and forces me to drive with the radio off now as it is so annoying. But the dealer can't find a problem as when I get there it has stopped.