Red everything is opening in Sandbox.

I have never used it. Not ever. Don’t have a clue how.
For what it’s worth.

This is what is written in the unresponsive script box for details. I tried to show you a screen shot of the message so you could see the little Avast sandbox tab which now atteached to everything! But file upload is also unresponsive now. Just hangs and hangs.
All I can say is that everything is opening up in sandbox.

I will try the repair now.

Problem signature:
Problem Event Name: AppHangB1
Application Name: firefox.exe
Application Version: 39.0.0.5659
Application Timestamp: 55933a80
Hang Signature: 7f6c
Hang Type: 0
OS Version: 6.1.7601.2.1.0.768.3
Locale ID: 1033
Additional Hang Signature 1: 7f6cc1e50782bcab1033e081d772481c
Additional Hang Signature 2: e684
Additional Hang Signature 3: e684d34bc6492ff1b222b4344e445d41
Additional Hang Signature 4: 7f6c
Additional Hang Signature 5: 7f6cc1e50782bcab1033e081d772481c
Additional Hang Signature 6: e684
Additional Hang Signature 7: e684d34bc6492ff1b222b4344e445d41