Thanks Darryl, I trashed Prefs but still no good .
Here is a more detailed description of whats happening.
Upon initial pro tools 12.8.3 , start up procedure ..., ie;
- during when the plugins are being loading into pro tools - ie; upon pro tools initial start procedure ,
This plugin load up stage gets interrupted by a
pop up window from avid stating : 2 fatal error messages from avid .
listing :
- 'tube-tech CL1B'
- 'UVI Workstation' .., both of which also informs me
I must contact the software publisher.
The Full error message from Avid reads exactly this ..., (same for UVI)
" FATAL ERROR TUBE-TECH CL1b ,
Tubetech CL1B could not be loaded. Please contact the software publisher for support using this software.
Error Details : TSS : Resource Temporarily unavailable"
NOTE : after I press the
OK button which is contained within in the message window,
Then Pro Tools itself - Then Crashes
(which was in it's mid startup/ plug in load up stage) ?
PS : BTW, Both those problematic plugins were the absolute latest versions available. They also both previously worked fine in pro Tools 12.8.2 ?
I am using :
- Mac OS = 10.12.6
__________________________________________________ _______________________________________
#1 : NEXT - TROUBLESHOOTING ... (after again trashing
PREFS)
I Moved those 2 plugins that had the fatal messages (ie; UVI workstation, and softube's tube-tech CL1B) into the unused folder
Result = Pro Tools seemed to load the plugins OK, 'up to' those starting with the letter 'T' (ie; alphabetically 'before' the tube-tech CL1B)
BUT ...., then pro tools crashed (showing the unexpected crash message, which asked me to send a log to AVID) 
__________________________________________________ _________________________________________
#2 : NEXT ... (after again trashing PREFS)
I moved
ALL PLUGINS .., to the Unused plugins folder
Result = Pro Tools managed to open (so far so good)
__________________________________________________ ____________________
#3 : NEXT ... (after again trashing PREFS)
I Moved All Plugins alphabetically back into the AAX Folder ..., "starting from plugins beginning with the letter 'A' , and all others up to those beginning with the letter 'T' , but stopping before the 'Tube-tech CL1B plugin '
(which was the previous problematic plugin that triggered the fatal message - so kept that one and UVI Workstation in the unused folder - and ALL others after the letter 'T' still remain in the unused folder ) ,
Result = yes AGAIN pro tools managed to open (so far so good)
__________________________________________________ __________________________________________________
#4 : NEXT ... (Now that pro tools
opens with all plugins loaded up to the problematic 'TUBE-TECH CL1B' ) ....,
I moved the REMAINING Plugins after the TUBE-TECH CL1b - back into the AAX Folder "EXCEPT" ...,
- UVI Workstation (That previously triggered the Avid Fatal error message) & ,
- TUBE-TECH CL1b
(I kept both these in the unused folder)
...., and then opened Pro Tools/ started up pro tools.
Result = yes pro tools managed to open (so far so good)
The WEIRD thing : is this method worked - but STEP
# 1 did not work ?
(ie; when I added those problematic 2 plugins to the unused folder back in step # 1) ?
__________________________________________________ ___________________________
# 5 : NEXT ...,
I have sent off support requests to UVI and to Softube .., so I will await their reply
Anyway , once again
Thank you for your help Darryl , much appreciated ,
..., and
Merry Xmas
To you, and to all the helpful members here in this community