I haven't used it on windows7 but I can tell you my first storm ALWAYS froze my computer when I connected it. I couldn't find a fix - ended up going in to Verizon, telling them, and getting a new phone. I haven't had the problem since (just loads of other problems instead lol).
This is a possible issue with your hardware/driver interaction in the new OS.
First update your BIOS on the laptop. Go to website for your laptop maker and grab the update file for it if available. Apply it and test connectivity. If that doesn't fix anything, uninstall DM and all OSs off your laptop, reboot and reinstall. Then plug BB in and let the drivers load. If it still freezes, you may need to step away from W7 until your laptop maker makes a reliable BIOS for it.
Posted from my CrackBerry at wapforums.crackberry.com