Just about every time SH4 starts acting squirrely on us (technical term for unascribed anomalies) the solution can be found in Doolittle81's post: Total uninstall and clean reinstall. These are very complete step by step instructions to accomplish that.
Three times I have had problems ranging from squirrely keys:p to CTDs. All three times this fixed it. If you are having weird problems happening, please believe that Silent Hunter 4, either 1.4 or 1.5 is a very stable game with very few fatal errors. Most of us have run it for months without freeze-ups or CTDs.
Please try Doolittle's procedure before you ask for help. I'll bet you won't have to!
