Hi Brian, hope you are enjoying your retirement! You mention the server, is the share access getting knocked out maybe? Does a repeating loaded ping work for more than 5 minutes?

Agree it's not likely crystal if crashing is random. Sounds environmental, maybe the upgrades were associated with other changes as well.

The full crash behavior suggests to me that file access to the programs and data might be getting cut, one way or another. I'd look at isolating antivirus next if the share access looks consistent.