Cubase pro 8.5 64bit not properly closing down

Cubase pro 8.5 64bit is not properly closing: after exit remains keep running, thereby interfering with other programs and Cubase pro restarted. In my case the audio via Focusrite Saffire doesn’t work properly any more. Win 7 64bit, Intel i7, 16 GB ram, ASUS P series mainboard. - F

ADDED info: I have replaced the Firewire Saffire Liquid 56 with A RME UFX. Both were and are connected BTW, using ASIO, and asio guard was off to reduce processor load. These problems were still there, but after that i uninstalled all firewire 1934 card drivers, and let windows re-install them. Had problems still, but differently: this time some audio and midi tracks in a complex arrangement did not sound on play back and some times a recording input was not responding. Rebooting the PC in most cases solved it, so maybe a windows 1934 diver is the cause? I went back to Cubase 8.0.35 yesterday, and this seemed to work.

MEANWHILE i went back to Cubase 8.0: no problems with non sounding or wrongly routed and addressed tracks. Cubase 8.5: i want my money back !!