logon to your webconsole with an admin account and select the Manage Nodes button. If you sort by Vendor the unknown nodes folder should show up.
Select the Unknown folder and check the box for all nodes ( under Add Nodes ) and all nodes will get selected. Hit delete and it will be emptied.
Let me know if this has helped.
That worked. It just took forever to delete. I could only delete 2,000 nodes at a time. After about 2 days. I was able to get it to delete. I just had to take my time with it and not rush IE to update.