First, save the game immediately assuming it's getting far enough to save. If it isn't getting that far, save the log.log file in the main game directory as log.txt as the modder may need a copy of it to figure out what the problem is.

Second, make sure it actually is the mod that is the problem, as there have been several issues brought up recently that are actually part of the base game and should be addressed to the devs. Remove all mods (remove the cfg, gui folders from the main game directory and, from inside the scripts folder, the core and the mods sub folders) and start a brand new game and see if the same problem occurs. If so, then it's a problem with the game and you need to let the devs know foloowing the procedures pinned in the main forum.

If the game itself is not the problem, try installing just the mod you suspect is the problem and see if the issue recurrs. If it doesn't, remove it by removing the folders as described above and try another likely mod by itself until you identify the one that is a problem. Once you do post a description IN THE MOD'S DOWNLOAD THREAD in the Released Mods subforum or if it is not one the mods there, wherever you downloaded it. This way the modder will be notified of the problem and will know which mod is (likely) the problem. State the version number on the mod and if there are both stand alone and mergable versions please identify which you are using as they may have different issues. If you are using FVModSync to install please include the version number for it as well. Please describe as clearly as you can what the problem is. If you are using other mods please list them all as well and, if you've renamed the containing folder, what you've called them.

Third, please be patient. None of the modders here are getting paid to do this and have other things going on in their lives, not to mention live in different timezones. It may take awhile for them to respond and may take much longer to fix it, depending on the issue.