You have something corrupted that's all I can say.
I have nearly 190,000 assets installed with zero errors. This includes many, many, many locomotives from Jointed Rail and other sources as well as assets and routes I imported from various places including my own creations. This makes about 170,000 non-built-in assets with some being quite old such as a couple of routes which date back to 2003 and 2005 respectively which I worked on back then.
So you need to check further. Installing the program may not be necessary, but reinstalling corrupted content maybe required. Once installed, ensure that all content is up-to-date, including that installed from Jointed Rail. They have done some updates to various components recently so ensure your scripts are up-to-date as well as cabs, engine sounds, and other components.
Once you've updated and installed, ensure there are no missing dependencies or assets open for edit. If there are any built-in/payware from N3V assets open for edit, you need to revert them to original - right-click on them in CM and choose revert to original with the assets highlighted.
If any of these conditions are there, you'll have problems. If there are any faulty assets, post the errors in a separate thread, and someone will assist you with the repairs. Most of the issues are pretty simple to repair if there are any.