Computer won't recognize BB--sort of

Here's the problem...and yes I've read all the other threads. I can hook up my new Storm 2 or my wife's Tour to any computer and what usually happens, or happened with all the other BB's I've had doesn't happen with these.

The normal reaction is the computer (PC) says it is installing software and says it' installed. I go to the desktop manager and sync my device, sync my media and all is wll. On these two machines, it's different. The desktop manager shows the pin and all that and syncs, but when it comes to installing the drivers for the phone, it just doesn't do it for either phone. that means media sync won't work (keeps telling me to activate mass media mode, which is already activated on the phone) and won't sync. It won't read the media card either.

Anyone got a clue on this and thanks.