There seems to be something strange going on here, you have Arduino AVR Boards 1.6.17 installed but there must be an old copy installed somewhere that Arduino is using instead. Please do this:
- File > Preferences > Show verbose output during: > compilation (check) > OK
- Sketch > Compile/Verify
- After the compilation fails you will see a button on the right side of the orange bar "Copy error messages". Click that button.
- Paste the errors here using code tags. If it's longer than the forum will allow then attach it as a .txt file.
I also assume having two versions of the Arduino programming software (1.6.0 and 1.8.1) on the same PC is not an issue?
It's certainly possible to have both. I have both installed on my computer without any problems. It is possible it's the cause of the problem but I don't think uninstalling 1.6.0 would solve it.
Below is a link to my dropbox of the screen shot capture of the Arduino AVR boards screen. This is the first time I have tried to use drop box as a link, I hope this works for you.
Using dropbox for the screenshots has similar issues to attaching a .doc file. Some forum users will just skip over your post when they see that, those might be the same people who could have helped you if you made it easier for them to do so. When you need to post images you should attach and embed them following these instructions:
that will get the most eyes on your issue.
When you post links please use the chain links icon on the toolbar to make them clickable. Otherwise we have to copy and paste the URL, not so hard but you want to make it as easy as possible for us.