I am all the way MAC but have a PC Laptop I maintain to service my two Blackberry phones. My DM will freeze up the laptop if I plug in the phone before activating the DM. So I must open the DM, plug in the USB cable and then plug the USB cable into the BB in order for the process to work well. My laptop will also not startup with any USB cable plugged or thumbdrive plugged into it.
Additionally, my DM did not initially run at all after the initial install. I uninstalled, reinstalled and still a no-go. I think it was conflicting with some software I had installed on the PC. So I reformatted the hard drive, installed only the XP OS and then the Blackberry DM. Then it ran. But PC's are notorious for 3 party app complications. This is why I am now a MAC user.
Hope this helps.