Logitech VX Revolution problem

I have purchased VX Revolution and received it today. The mouse is quite good except for a few problems that I am experiencing.

The first problem that I encountered was the middle button, pressing the wheel down. It was very difficult to click that button and I initially had to put huge amount of force for an electronic device to actually get it work. This problem is almost gone once I held the button down quite hard and rotated the wheel a few times.

Another problem, the problem I'm writing this thread for, has to to with inactivitiy. If I don't use the mouse for 10 to 20 seconds then rotate the wheel by "one click" in ratchet mode, nothing happens. I have to rotate it once again then it starts to scroll.

I have initially thought that the mouse automatically disconnects but if I press other buttons after 10 to 20 seconds of inactivity, they respond and work perfectly.

I have tried it on my laptop (Windows XP SP2) and my sister's (Vista). I have tried embedded mode (without the software) on my sisters laptop and full mode on mine but the problem still persists on both of them. I have tried different USB ports for the receiver but same thing happens.

Can anyone please help me out? Is the mouse defective? I have purchased it from an online store and they agreed to give me a replacement if I can tell them if this problem does not happen on other units. Can anyone tell me if it happens on theirs?

Any feedback from the users would be appreciated as well as I can then see whether it's supposed to happen or not.

Thanks for your help