To setup/view your slingbox:
You can download an older version of firefox from here:
I downloaded 32 bit version of firefox to be safe. If you run into a plugin corrupt error after logging in, do the following:
In the address bar type: "about:config"
A message will pop up for dangers of the these options agree to them if you would like to continue.
Search for "xpinstall.signatures.required". It should have a value of True.
Right click on "xpinstall.signatures.required"
then click on "Toggle" the value will change to false. After that just restart Firefox and try watching your Slingbox.
I managed to do a fresh install after hours of trial and error. Also, you can view/setup by downloading an older version of the app here:
Version 2.0.4 works fine