Can you disable the antivirus while playing the game? I use Microsoft Security Essentials and have no problems and it works well and it's free. I am unfamiliar with the hidden skills mods so I don't know how that effects the game or needs to be updated when there is a game patch. Did you try resetting the game? Here is a link - reset game This will tell you if user data is causing the trouble or the game files are corrupt.
I tried disabling the antivirus, which didn't work. My computer already has Microsoft Defender installed already, but I got Norton as a free trial. The Hidden skills mod is used by a lot of people, and doesn't cause any problems that I know of that stop the game from working. I tried resetting the game following the instructions, but that didn't work either.
If the reset didn't work that means something is corrupting the game files. This type of error means the application can't find a file like a .dll file. This is usually caused by something blocking or corrupting the installation. Sometimes a manual uninstall and reinstall will fix this problem. Did you enable .net framework in windows features?
Using restore should be the absolute last thing to use if all else has failed as at this point you don't knowwhat was restored.
