I am having a video sync problem with my Slingbox 500.
Essentially, after some variable time, the picture loses line sync, and the bottom half of the screen becomes a set of regular offset diagonal lines. Note, top half of picture is still there, though the vertical aspect may be slightly off. Audio seems fine.
At the Slingbox End:
Cable box connected to Slingbox. Sling connected to cable modem via ethernet.
At the viewing end:
Cable modem connects to Google chromecast via ethernet, Cable modem connects to device over 2.4G wifi.
Before the problem happens, the picture is great, the sound is great. Other applications that have casting functions work fine without the random failures (ie: Netflix, Amazon through browser, etc.)