SERVER_MS_NOT_AVAILABLE Internal error during authentication - client side

Hi Experts,

I reviewed the various threads here concerning this topic, and not found one that fits my situation. We have a well functioning SAP-PI 7.11 landscape, and normally 10+ support team members connecting with no issues. Except for a 2nd PC i have just installed. Our normal desktop is Corporate imaged XP PC. my problem child though is a Linux PC (I would think it should be the other way around 😊) Anyway the Linux box uses the exact same LAN, same DHCP, same DNS server as it's XP brethen. it connects to the http portion of PI just fine, but fails with the SERVER_MS_NOT_AVAILABLE error when I attempt to connect to the ESB or IB. Just to be safe I have placed the FQDN of the PI hosts into the Linux hosts file. no effect. What am I missing? Anyone else ever see this? suggestions on troubleshooting?