Landscapematerial- and Buildproblem

(Sorry for my bad english, I’m a German guy)

Hello Guys,
I am new at Unreal engine 4 and I haven’t got much programming skills.
I have two problems:

  1. When I create a Landscapematerial (with 4 textures) and add more later and I want to create Layer infos for the new textures and I choose a folder there is an
    error which says: “Name may not contain the following characters:”
    Then I can use the texture with my Landscape but when I save and load all Layer Infos from the new textures are deletet and I can only see the texture (on the Landscape) which I
    added when I created the material.

Landscapematerial: (click)

ERROR: (click)

  1. When I add an self-created object (without textures) and I want to add a material from the starter content, the material on the object is just an blurry mess and you only see 1-2 colors.
    When I click on build in the middle of the progress the programm craches and I have to restart the pc. My world consists of very much objects. Can that be the mistake?

Object with blurry material: (click)

World: (click)

Thanks for help,
LG edd