Try this :
Go to WINDOWS settings
On system
click on default programs(left side)
scroll down and click on " choose default value for the application" sorry I'm french
let's load and click on opera stable (left side)
click on 'choose default settings for this application"
check all BUT NOT
CRX
NEX
PDF (if you want or not)
FTP
MAILTO
click on save at the bottom right