I think I may be over the hurdle on this.

Digging deep down into the SQL Network Configuration, I noticed that Named Pipes was not enabled. Once I enabled this,...

SQLAssAS (2/23/2015)

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you mention windows update - has SQL been restarted as a result of updates, and a new port has been picked up?

Check the port number and add it to...

Lowell (2/23/2015)

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the full error message would help; my first google for SQL server error 17 seems to imply

SQL Server does not exist or access denied.

i'd just assume it's time...