Windows 10 Pro issue

Server:  Windows 10 Pro system
Postgresql:  8.4.5 installed several months ago and working correctly,
until recently

On Feb 9, 2018 about 7 PM pg_log file recorded:

2018-02-09 15:04:23 CST LOG:  unexpected EOF on client connection
2018-02-09 19:12:41 CST LOG:  received fast shutdown request
2018-02-09 19:12:41 CST LOG:  aborting any active transactions
2018-02-09 19:12:41 CST LOG:  autovacuum launcher shutting down
2018-02-09 19:12:41 CST LOG:  shutting down
2018-02-09 19:12:43 CST LOG:  database system is shut down

On Feb 12, 2018 about 2 PM after computer was restarted, pg_log file
recorded:

2018-02-12 14:17:31 CST LOG:  could not open configuration file
"C:/WINDOWS/system32/ConfigDir/pg_hba.conf": No such file or directory
2018-02-12 14:17:31 CST FATAL:  could not load pg_hba.conf

The log event on Friday, appears to have recorded a forced shutdown -
Windows 10 update install, maybe?  No one at business to record what may
have happened.

On Monday afternoon, postgres service refused to Start as indicated in
that day's log event.

Any ideas as to what might have happened, or caused this anomaly? It's
almost as if some Environment Variables were missing, or scrambled.  I
don't think Postgresql uses the Windows Registry, in place of EV's, does it?

Dale Seaburg