The main problem is the game is old, and the OS is new, the hardware is new. The game was written before the dawn of using 1024x768 resolution, much less wide screen resolutions. One thing you mention that is intriguing is that things "change" as you are attempting to play the game. This brings up a couple of questions, the main one being "Where is your game installed?"
The game's installer defaults to a "C:\Program Files..." folder path, no matter if you have a disk version, Amazon or Steam download, or whatever. If you are installed there, a lot of mods will not function there, because Windows prevents any changes made "keeping". You will need to change or move the installed path to a folder of your own naming. This also brings a 2nd question: "What game do you have, Steam, Amazon, or disk, etc.?" A Steam game is more difficult to move - er, rather, more time-consuming, not difficult...
It would also be helpful to mention some of your computer hardware, such a computer model or the cpu, the amount of RAM, your video card, the OS you are using and its bit-depth (32 or 64-bit), if known.
