constant use of killall Finder
Before we begin: Make a backup of your Data e.g. with Time Machine or similar Software (if you not use Time Machine).

Note: All steps are complete in itself. If one of the steps work, you're done. 

Step 1: Boot into Safe Mode


Restart your mac and hold down the Shift-Key during startup.
The startup process is slower and possible you got a flashing screen. This is normal.
Login and open the Disk Utility. Choose your Systemdrive and click on the buttons Verify and repair disk permissions.
Restart the mac and test.


Step 2: Finder Preferences

Sometimes the Finder Preferences may be corrupt so you can delete this files to return to Standard configuration.


Click on the Finder Desktop and press the keys Command + Shift + G
In the small Window copy and insert the following Line ~/Library and press Enter.
Search for the following folders and move the bold-marked files into the Trash.

~/Library/Preferences/com.apple.finder.plist
~/Library/Preferences/com.apple.sidebarlists.plist (if exists!)
~/Library/Saved Application State/com.apple.finder.savedState
~/Library/SyncedPreferences/com.apple.finder.plist


Note:
Maybe some of the files (folders) not exist on your system this is ok. 
Please don't delete the files until test that works.


Restart the mac and test