If you want accurate help, the first thing you should tell us is:
1.- Your computer specs (Specially graphics card and drivers version you are using)
2.- Version of SH2 installed (Initial 1.0 or patched to 1.1)
3.- Mods you have added (Or if you have a plain vanilla install)
4.- It also would be helpful if you could copy here the janus error you get. That is many times very telling of where the problem comes from.