The graphics issues are probably caused by an incompatibility with your old integrated graphics chip. If they didn't occur before you changed the settings, you can try if deleting the file prefs.prop from the save game directory helps.
I don't know what's causing the save game issue though. There is a different save game issue, that sometimes occurs, that can be bypassed by starting the episode with the respective link from the start menu. You can try if that helps here too.
You can also try if right clicking the episode and selecting "run as administrator" helps.
I am a Community Moderator, and I am here to keep the Forum a fun place for everyone.
My posts represent my personal opinion. I am a volunteer, not a TTG employee.