Adobe Reader DC unworkable

Well, i did a little more research and it seems like playing with registry keys is the only solution.

The strange thing in your screenshot is that you have Reader DC. Which should have an option to hide the welcome tour..

Versions 10 and 10.1 of Adobe Acrobat did not have this option to hide the welcome tour so the only available solution was to apply the registry key fix like shown hwre:

https://helpx.adobe.com/acrobat/kb/hide-welcome-screen-acrobat-reader.html 

This makes me wonder if you had Adobe Acrobat X installed before in your computer and then upgraded.

The darkening of the screen is another odd behavior.

Like Test Screen Name piointed out by saying "all sorts of nasty effects", you are going to need to download the Adobe Repair and Cleanup tool which does have an automated process to clean orphan files and old or corrypt registry keys from a bad installation or product registration

Here is the link for the Adobe Acrobat And Reader cleanup tool:

https://labs.adobe.com/downloads/acrobatcleaner.html 

Here is a link for the Adobe Creative Cloud cleaner tool from here:

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html 

Limited Access Repair tool fix here:

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html 

Adobe Licensing Repair Tools from here:

https://www.adobe.com/support/contact/licensing.html 

The take a tour issue suggests a problem that needs fixing that will have all sorts of nasty effects. Need to sort that out. It's probably an %APPDATA% foder pemission issue.