What you describe suggests to me that the mod you installed is old, incompatible with your game version, or installed incorrectly. If you dowloaded BetterRepack R4, almost every mod you could ever want is included with the STN repack. Of course you can add more of your own personal taste to the game later.
Getting back to game issues as described. Most MOD files have a read-me written by the mod author which normally indicate where to install them, but not always. If the MOD says in the game root directory, be very careful to determine (what directory) because ROOT normally means the same directory (folder) where the game start executable (*.exe) file reisdes. This is not always the case because there are subfolders within the game directory specifically named "plugin" "script" "mod" so you need to be sure you put your new mod in the correct folder. As a helper some good modders will show you where the fille or file set should reside by naming the main folder, then child folder(s) to be specific.
In the event you or anyone else totally borks the game after one mod install, you can find it by looking in downloads or wherever the original mod was and review the contents of that folder.. go back and delete that content from the game and you will be fine.
As an added precaution, I run the registry_fix batch file in the R4 Repack after "fixing" a boo-boo I made.
