What he's talking about are Windows folders like "users" that are super protected be the operating system.
There is no end to the unexpected things that will happen, or not happen, to your files.
If you only have a C:\ drive then you should put your stuff in the root of that drive.
Something like C:\Train stuff. If you put a 1 in front of it it will pop to the top of the list, C:\1Train stuff.
You'll want to keep the Openrails stuff by itself. C:\OR or something.
Randy