No list!
Hopefully this isn't a hardware problem, meaning a failing hard drive. I recommend running some drive diagnostics. This may explain why stuff appears after restarting your computer. (cringes inside!).
HD Sentinel
https://www.hdsentinel.com/index.php
There's a free version which will suit your needs. Be warned, the diagnostics can take sometime, but the other information such as drive health are available immediately.
If nothing appears out of the ordinary there, try this:
1) Run a database repair. You can do this by clicking on Developer and then Rebuild database right on the Launcher.
2) Once that runs, start up content manager.
This may run for a bit as the data is validated. "Validated" is a compartment word for a bunch of things that go on as content is cached. Depending upon how much stuff you have, the progress bar may take "sometime" to complete and for content to reappear in Content Manager.
3) Before you start up Trainz, I recommend defragmenting your hard disk if it's not an SSD.
Good luck.