after some tests and reading the manual and Ableton support, maybe I fixed my issues, likely linked to a PC barely reaching minimal specs, notably low in RAM and CPU cores, and to Ableton live project previously placed in an external slow drive
the fix simply involves moving Ableton live project in the main SSD drive and freezing lanes just after I hear that they are all fine
in my 1st test with 4 guitars Rocky-4guitars.xml (23.9 KB) I used my preferred workflow that is:
1 - selecting a preset that sounds suitable to my ear
2 - changing some of the chords that don’t have the right sound
BTW the patterns I love more are 5/4 phrase so I hope they will increase 
3 - starting with all pattern slots identical, then changing something but not so much: I like that some melody is easily recognized, but not too much to seem repetitive, so I always search for a balance
4 - when done I use MIDI capture then drop the MIDI in the lane and FREEZE it, then I repeat the search for the other lane
freezing all lanes keeps Ableton CPU level to about 10%, while using unfreezed lanes push it up to 30-50% and over up to a crash
and here are my specs:
I see the audio card is not showed: it is the Komplete audio 1
finally I’m fed up with Ableton
acquired Reaper 6 and no more crashes, even uploading Ableton in Reaper!
MOJO!
(cit. Carlos E. Arellano)
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just arrived today from the Ableton support
Hello Claudio,
Thank you for your inquiry.
The Crash Report shows that the VST Scaler 2 plugin caused Live to crash.
To potentially solve this problem please update the plugin and/or test with the VST2/VST version of the plugin.
Crashes related to specific plugins are generally the result of the device itself crashing, which takes Live down with it. And, since Ableton Tech Support Agents are not trained on specific third-party devices, you would receive much more specialized support from the developers of the plugin.
Let us know if you have additional questions. Thank you.
unfortunately, I’m experiencing many crashes (or freezes that go to a crash) with Reaper as well 
as far as I find some time I’ll do further testing to see if it’s really Scaler to do the mess
I am not sure it’s my weak PC, because Ableton worked smoothly up to a bad day when it started to crash (and it was before Scaler), and no Windows (or other software) update came before or just that day
I am also using this tool but no result so far
I’ll let you know if I find the culprit
