After some troubleshooting< I determined the following:
Older Omega2+ (with older firmware) worked as expected. No problems connecting using SSH on PuTTY.
I was able to connect to my new Omega2 using SSH on my older computer which had an older version of Putty.
I uninstalled and removed all Putty files (not as easy as one would hope) then reinstalled and tried again with the same results.
Finally, I noticed that I had the 32-bit version of Putty and installed the 64-bit version instead. That finally worked. So there is something with using the latest 32-bit putty on 64-bit windows that gives this fatal error with the latest version of Omega2+ firmware when doing SSH.
At least it's working now so I can move on to the next step.