Cubase 6.5 problems

i would like to describe your me specificaly what is the problems, but the main issue that i can’t understand it.
Cubase 6.5 purchased 4 years ago , i had no problems till the last 6 months and it just getting bigger and bigger.
Non stop audio dropouts , then some plugins as Serum & spire started to dissapear while im working.
like i’m openning a serum / spire / omnisphere / nexus or any other vst , choosing a sound , working , then i’m duplicate or openning a new instrument track , choosing one of the plugins , it’s open nothing and left me with empty instrument and a lot of maddness.
Another problem is that while im trying to work the project suddenly crashing and writes “runtime error visual c++” or something like this and shutdown the program.
it’s not a computer issues cause im on a new studio pc cost me enough to know that he is okay and the plugins and cubase installed on ssd .

Cubase 6.5 32Bit ,
Windows 7.