You may want to check on drivers and/or windows updates. Depending on which notebook you have, and which OSX disc you used to install the bootcamp drivers; their could be an issue hidden there. After a 7 x64 install I typically run windows update first for drivers, then install the bootcamp drivers from my original system disc. In my experience, I've run into systems which had bootcamp drivers installed from a differing system disc. Also check and see if an update has corrupted the system somehow, or if there is some hidden process causing the system to hang at shutdown. This can be found in the logs under computer management.