Here, take a look at this article:
As long as you're using a browser/operating system combination that shows it is supported in this article, with just one exception:
The Slingplayer plugin for Google Chrome was changed to an extension (as opposed to a plugin) when Chrome changed to a 64-bit browser from a 32-bit. Unfortunately, because of this change, the processes to set up a Slingbox are no longer compatible in the Google Chrome browser (even though the Chrome extension that can be used to watch/use a Slingbox is still supported).
Also, take care to make sure you're not using the Microsoft Edge browser. The logo for this browser is quite similar to the Internet Explorer logo, and will also give you the error you mentioned above. Your computer should still have Internet Explorer - I would suggest doing a search for it just to make sure you are using Internet Explorer. As long as you use Internet Explorer or Firefox, you should be good to go.
Hope this helps!
I give up! IE won't work. I tried Firefox and it seemed hopeful until I got to downloading the add-on for Firefox and it wouldn't execute, saying "The add-on downloaded from this site could not be installed because it appears to be corrupt". I also got a message saying that my browser settings prevented this happening.
I think the Slingbox is due for the rubbish bin! (Unless anyone can come up with a workaround in the next few days!)
For Firefox, take a look at this thread, where one of our moderators found a solution to the exact error you're seeing:
What errors are you seeing in IE? Is it still giving you the same message you were seeing before?