If you had the installed previously, there will be an old Save folder that should be deleted. You should find it in the path "C:\Users \YourName \Documents \SH4" ("My Documents" in 10??). You can either delete everything below it, or delete the whole SH4 folder. The game will recreate it again when you start SH4.exe the next time. There might be something in there messing with your current graphics card. If the Submarine School and the Quick Missions work, you should be good to go... Let us know!
