Do modifications contribute to more frequent game crashes?

I have been using a few modifications recently and I noticed that my game crashes after two-three hours. I currently run on pretty low graphics settings with Smart RAM. However, when I first purchased the game it ran for six-seven hours without crashing (using medium settings without any programmes to aid it). So, my question is - do modifications contribute to more frequent game crashes or is it the fact that I've racked up so many hours on the game? I frequently defragment the game files and delete save game files I no longer use.

Thanks in advance.

Some can. Darth would be the first suspect. I am sure there are others.

Some of the NTW mods are very unstable, they would be likely to cause issues. Then again some are fine, so it depends what you are using.