UE4 Doesn't re-open after Minimizing

I would like to add that when I do start up UE4 and the window opens (windowed), i found that it responds when I holding down on the mouse left button anywhere in the window, but as soon as I let go - it stops responding.

Everytime I minimize UE4 and attempt to RE-open the UE4 client, the window doesn’t maximize or open at all. I click on the UE4 icon to try to re-open (maximize)but still doesnt work
im using win 8.1. I have done a windows refresh so its reinstalled windows and excluded any updates that was released this 2016, but the problem is still happening.
I open task manager and it says UE4 - Not responding. 2 weeks ago it was working just fine.

Epic games launcher minimizes and maximizes with no problems at all.

Any help? thanks