Hi,

That's a lot of strange stuff. I am sure we will see the solution but it's always useful to provide the following so we can see what you have installed, which hardware you are using and how your project and solution files are named :_

Switch on vmicro>compiler>verbose and also the "vmicro>show build properties". Then build a project and copy the resulting output into a new text .txt file. Then email the file to info[at]visualmicro.com along with a link to this post.

Please also show an image of your full visual studio ide with the solution explorer open and project/source codes expanded so we can see the name of the project and files.

As for VS launching the arduino ide I have never heard of that before, might be useful if you zip and email your files from your project folder so I can see the config.

Thanks.

Hello Mr. Leek,

Thanks for your excellent and quick service! 
1)  You are right, I don't understand what happened but this problem is solved.
2)  I installed version 1702.15 but this didn't clear the errors. I discovered an installation error with Time.lib but that also wasn't the solution. 
After Googling quite a long time I found the way out. Very strange:  it was an extra   #include <TimeLib.h>  besides the  already existing  #include <Time.h> .
I think it is an Arduino V1.8.1 issue because this problem was not present at version 1.6.x.

But now all works fine!