How to solve unity interface issue with dropdown list?

Question

C++ / C#

The essence of the problem:
I click on the drop-down list, it is displayed normally, I start to move the cursor down the list from top to bottom, then the list items start to look like I attached it on the screen. Plus, when you hover over the "orange rectangle" zone, this zone becomes orange. Attached a screenshot

In the early days there was no problem. Appeared 2 days ago. Reinstalled wood. Reinstalled Unity. Could not solve the problem. It was not possible to google information on this issue.
Unity version:
Version 5.4.2f2 (b7e030c65c9b) Personal
Wed, 19 Oct 2016 15:48:54 GMT
Branch: 5.4/release
PC: i706700k 4.00GHz, ram 16 gb, GeForce GTX 1070 G1 Gaming, dell up2516d 2k 25''

Answer 1

And what kind of overlay buttons with a microphone and a prohibition of rotation (probably)? It is very similar to some kind of third-party software, with which the conflict arises.