Cubase Randmoly Deletes Plugins

Hi Guys!
im already pretty desperate about it…tried almost everything, nothing seems to fix this problem.

my cubase 8.5 randomly deletes instruments from “instrument track” - the track itself and the midi information stays the same but the plugin instrument is deleted : , once i save a new version of the project cubase will remember this and never load the plugin again, but if i go back one version before it happened the plugin works as usual.

also when cubase deletes the plugins it dosent warren you or give you a log when u open the project, and even if the plugin was unload, u can still open a new one which works fine - so it dosent have nothing to do with plugin load at start-up i guess.
the same thing happens with inserts effects on the mixer :

it get so bad where i have to copy half of my instruments from older projects and makes the software unusable!
at this point i have too much work to do and have projects from customers coming back because they missing parts of the track :

help plz!

I have the same Issue. With inserts and vst instruments on Win 7