Yesterday I removed enough old crap to give 65 GB free space. Crashed twice already this morning. Might be the hard disk, but my boot camp partition running Windows 7 never crashes!?! At the time of the last crash TimeMachine was backing up, only Safari was running and I was writing this reply. Could not find a crash report, so here are the messages from Console (system.log) just prior to the last crash:
Jun 29 07:59:48 john-mcdonalds-macbook-pro blued[90]: hciControllerOnline; HID devices? 1
Jun 29 07:59:48 john-mcdonalds-macbook-pro blued[90]: hostControllerOnline - Number of Paired devices = 0, List of Paired devices = (null)
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: MacAuthEvent en1 Auth result for: 90:27:e4:5c

c:32 MAC AUTH succeeded
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: wlEvent: en1 en1 Link UP virtIf = 0
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: AirPort: Link Up on en1
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: Got incomplete channel sequence length 0, should be 16
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: en1: BSSID changed to 90:27:e4:5c

c:32
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: en1: channel changed to 149,+1
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: en1::IO80211Interface:

ostMessage bssid changed
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: AirPort: RSN handshake complete on en1
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: in6_unlink_ifa: IPv6 address 0x2e08cad084cbaf25 has no prefix
Jun 29 07:59:51 john-mcdonalds-macbook-pro configd[57]: LINKLOCAL en1: parent has no IP
Jun 29 07:59:51 john-mcdonalds-macbook-pro kernel[0]: Unexpected payload found for message 9, dataLen 0
Jun 29 07:59:51 john-mcdonalds-macbook-pro launchd[1]: BUG in libdispatch: 15F34 - 1718 - 0x0
Jun 29 07:59:51 john-mcdonalds-macbook-pro configd[57]: en1: address fe80::226:8ff:fee8:3237 not present/ready
Jun 29 07:59:51 john-mcdonalds-macbook-pro UserEventAgent[49]: Captive: CNPluginHandler en1: Inactive
Jun 29 07:59:51 john-mcdonalds-macbook-pro symptomsd[235]: -[NetworkAnalyticsEngine _writeJournalRecord:fromCellFingerprint:key

tLOI

fKind:lqm:isFaulty:] Hashing of the primary key failed. Dropping the journal record.
Jun 29 07:59:51 john-mcdonalds-macbook-pro configd[57]: network changed: v4(en1-:10.0.1.4) DNS- Proxy-
Jun 29 07:59:51 john-mcdonalds-macbook-pro symptomsd[235]: -[NetworkAnalyticsEngine _writeJournalRecord:fromCellFingerprint:key

tLOI

fKind:lqm:isFaulty:] Hashing of the primary key failed. Dropping the journal record.
Jun 29 07:59:51 john-mcdonalds-macbook-pro symptomsd[235]: __73-[NetworkAnalyticsEngine observeValueForKeyPath

fObject:change:context:]_block_invoke unexpected switch value 2
Jun 29 07:59:51 john-mcdonalds-macbook-pro netbiosd[246]: network_reachability_changed : network is not reachable, netbiosd is shutting down
Jun 29 07:59:52 john-mcdonalds-macbook-pro configd[57]: network changed: DNS* Proxy
Jun 29 07:59:52 john-mcdonalds-macbook-pro UserEventAgent[49]: Captive: [CNInfoNetworkActive:1748] en1: SSID 'John's Wi-Fi Network' making interface primary (cache indicates network not captive)
Jun 29 07:59:52 john-mcdonalds-macbook-pro UserEventAgent[49]: Captive: CNPluginHandler en1: Evaluating
Jun 29 07:59:52 john-mcdonalds-macbook-pro UserEventAgent[49]: Captive: en1: Not probing 'John's Wi-Fi Network' (cache indicates not captive)
Jun 29 07:59:52 john-mcdonalds-macbook-pro configd[57]: network changed: v4(en1!:10.0.1.4) DNS+ Proxy+ SMB
Jun 29 07:59:52 john-mcdonalds-macbook-pro UserEventAgent[49]: Captive: CNPluginHandler en1: Authenticated
Jun 29 07:59:52 john-mcdonalds-macbook-pro symptomsd[235]: -[NetworkAnalyticsEngine _writeJournalRecord:fromCellFingerprint:key

tLOI

fKind:lqm:isFaulty:] Hashing of the primary key failed. Dropping the journal record.
Jun 29 07:59:52 john-mcdonalds-macbook-pro symptomsd[235]: __73-[NetworkAnalyticsEngine observeValueForKeyPath

fObject:change:context:]_block_invoke unexpected switch value 2
Jun 29 07:59:54 john-mcdonalds-macbook-pro sharingd[287]: 07:59:54.024 : Starting AirDrop server for user 501 on wake
Jun 29 07:59:54 john-mcdonalds-macbook-pro kernel[0]: en1: BSSID changed to 90:27:e4:5c

c:32
Jun 29 07:59:54 john-mcdonalds-macbook-pro kernel[0]: en1: channel changed to 149,+1
Jun 29 08:00:30 john-mcdonalds-macbook-pro WindowServer[158]: _CGXRemoveWindowFromWindowMovementGroup: window 0x3b is not attached to window 0xc5
Jun 29 08:01:02 --- last message repeated 1 time ---
Jun 29 08:02:47 john-mcdonalds-macbook-pro com.apple.backupd[599]: Will copy (782 MB) from WarpDrive
Jun 29 08:02:47 john-mcdonalds-macbook-pro com.apple.backupd[599]: Found 4458 files (782 MB) needing backup
Jun 29 08:02:51 john-mcdonalds-macbook-pro com.apple.backupd[599]: 8.52 GB required (including padding), 883.9 GB available
Jun 29 08:03:00 john-mcdonalds-macbook-pro lsd[214]: LaunchServices: Could not store lsd-identifiers file at /private/var/db/lsd/com.apple.lsdschemes.plist
Jun 29 08:03:32 --- last message repeated 5 times ---
Jun 29 08:04:48 localhost bootlog[0]: BOOT_TIME 1467201888 0
The SSD is a nice idea, but I was wondering whether it is worth the investment as this machine will not run Sierra. Anyway thanks for your support.
John