i'll just copy this over from another one of my posts;
I have found the solution. first, put both Sengoku.exe and SengokuGame.exe into Windows XP (Service pack 2) Compatibility mode. then restart your computer. after the restart, run Sengoku.exe from the sengoku folder. make sure it is updated, then click play. it works fine.
if that failed to work, update ALL of the neccesary programs for sengoku (.NET, virtual C++, etc.) then try again.