Thanks, Ken. It seems that you had a different problem, which just happened to crop up at the same time as someone else's problem about the trojan.
It sounds as if your Shortcut for Sudoku was broken, for some reason. There could be lots of reasons for that, both legitimate and illegitimate.
When you went looking for it, you couldn't find sud.exe. Getting re-started from that situation can be problematic. It is a situation that confronts people who, for example, have had to do a Windows-sanctioned "System Restore".
Please look for this directory on your computer:
C:\Program Files\Common Files\MimarSinan\Installation Information\{FB5055E4-9BE1-425F-B40A-33E43E9460DA
Please delete the entire "{FB5055E4-9BE1-425F-B40A-33E43E9460DA}" directory and all of its contents. You will then have a clean slate. Then you can install the Sudoku program again, by Run-ning the SudokuSetup file.
- Wayne