Good question! A couple things to check is your browser and operating system. Be sure that it isn't 64 bit. Also, make sure you don't have any firewalls turned on through your router or computer while setting the Slingbox up. You want to make sure you are hardwired to your router as well for best results.
Here's an article that may help: My Slingbox doesn't show up on the network and the Network light keeps flashing
If this doesn't work, let us know!
Sling Media Forum Moderation Team