We have over 200 nodes in Orion showing as Unknown Vendor and Machine Type. These all appear to be our Windows XP desktops and when I try to 'Rediscover' the nodes in the detail panel, I get an 'Unable to validate this node with the supplied credentials' message. I installed SNMP on one of the workstations and rebooted just in case this was the issue but to no avail.
Windows Firewalling is turned off also.