Sorry you are having issues with SC8.
Probably not much help but you stated that you started having issues after the last update. I would go back to your original disk or download version you got from Tormach. That is probably the only one they will support, or whatever update version you got from them.
I can't help much as I still have SC7. Works flawlessly for me. When SC7 does get glitchy there are things you can do to fix it, don't know about SC8 though.
Gerry
Currently using SC7 Build 1.6 Rev. 64105