After a few minutes with an open file the screen flashes white and GPU preview support goes away. The GPU preview is greyed out. Interestingly I don't need to restart Illustrator, I just need to shut the file down an re-open it then GPU preview is back. The files affected have embedded images within them. I have an Nvidia 3080ti graphics card with an AMD 5950x running latest versions of illustrator (happens with the beta too though it did seem to last longer before the white flash) all drivers and os up to date.. Nothing to do with outline mode and rulers etc as all of those features are disabled and I still get the crash after a few minutes.