It is true that the SlingPlayer for Windows (Legacy Desktop Player) is not compatible with the Slingbox 350. If Newwatch.Slingbox.com seems to lock up when you use it on your secondary monitor, I would suggest trying the Embedded SlingPlayer. Below is a link to the Embedded Player as well as the FAQ for the Embedded Player:
Let me know if this works for you!
Sling Media Forum Moderation Team