:/ Tried fixing this It just didn't work

weeeeell
I've been getting a blank screen everytime i enter dueling network i tried the followings:
-Clearing cookies and cache
-Firewall is off ._.
-Tried The best 4 browsers: Internet explorer,Mozilla firefox,Google chrome,Safari
-Making a new account on the PC
It can't be from my connection though....Yes it is kinda crappy but i tried logging in on my sister's laptop and the screen showed and i was able to log in normally,aka me and my sister have the same Internet IP so it can't be from the connection :/ Heeeelp

Do you have headphones/speakers
this used to happen to me and as soon as I got speakers DN was working just fine for me

also updating flash player is a good idea!