[Help needed]Game's crashes while talking with various merchants

Hi Folks! I'm in a kind of a pickle here, had some problems with cromwell, meaning that when the banter that he'll look through my stuff for crafting ingredients starts the game crashed. The only probable reason i found was problem with the item upgrade mod. I've reinstalled that mod, and now the game crashes when i try to speak to other merchants too (the german accent one on waukeens promenade & the new one on Umar hills). I'm not very apt at this, so i'd be really greatful fo any advise how to troubleshoot & find a solution for this matter (if possible w/o loosing my saves). Cheers!