A new schema update was released today that includes support for JunOS 10.0r2.
There is another method that we have found reliable: The problem seems to be UAC and Schema Updates and the problem is present from NSM 2008 through NSM 2009 on Windows Vista and 7 (32 and 64).
The problem is sometimes intermittent and occurs after a fresh installation of the NSM client or after a schema update. It can show itself as missing devices in the device tree or strange problems in a delta configuration. If the problem has already occurred then any old schemas installed on the Windows Client must be deleted as covered in this KB article http://kb.juniper.net/KB14064. Alternatively uninstall the client, reinstall and then follow the step below before starting for the first time.
To avoid the problem altogether then either turn off UAC or always run the NSM client with administrator privileges. This can be set under the applications compatability tab "always run as administrator". This will not fix the problem if it has already occurred, you must first follow the steps above first.