Do you have ANY rewire client applications installed on your machine (like melodyne, reason, live etc..) from the ignition pack or elsewhere? If so, one or more of those are most likely not the leopard compatible versions and causing your issue.
The older version of Melodyne essential that comes in the ignition pack 2 would cause this until updating to the newest version 1.8.1.3. (You would also notice other music applications/rewire hosts like garage band either crashing or locking up at launch too.)
check this page for updates:
www.digidesign.com/leoplugs