I've been using Slingbox for several years. My new computer came with Windows 8.1(64 Bit) installed and now I cannot connect to my Slingbox. The screen says "initializing" and stays there, connecting via Windows 7 (64 Bit) and IOS 8 is not a problem. I am launching from Google Chrome. Any ideas I could try?
I would start with clearing the cache and cookies on your computer. This article below will have more steps for you to try to resolve this issue.
Hope this helps,