Agree, this is a frustrating problem, but guess what? I have a Roku media player, too, and it can freeze up as well. The "fix" is the same -- remove from power and restart after waiting to plug it back in.
The "solution" would be to have power switches on the WDTV (and the Roku). So, I created one for each by putting a plug-in power switch (obtained from the electrical dept of the home improvement store) between each unit and its power source. I also made it easy to get at by plugging both units into an extension cord to separate them from the other components so I don't have to dig back into the innards of the wiring all the way back to the surge protector to unplug them anymore. Now, when freeze up occurs I just flick the switches off and back on.
This seems to be how life is with gadgets without on-board power switches; especially internet-related ones. For example, I have a house wired for CAT-5, and in each of the four rooms wired so, I have added internet 4-port switches to split the internet signal from the router into more connections. Some switches have been connected for 10 years without a problem. But, last month I found that my bandwidth speed had reduced to almost nothing at two of these switches, and I had to remove power from both switches to fix the problem. Another brand switch was not affected by the problem. Apparently, some electrical gremlin came along that scrambled the brains of the two switches.
The take-away here is to periodically shut EVERYTHING down in the computer, media player, internet system, home entertainment center, etc. to clear out any electronic gremlins, and restart them all in a systematic way. Reboot the whole enchilada!
Sometimes the electric company does this for us -- when we least expect it or want it to! All equipment comes back on all at once when power is restored. It is after this event that I take the opportunity to turn off and on all equipment again one at a time in the order it ought to be done.
Added comment by author the following day: It appears I jinxed myself by writing the last paragraph above yesterday. . . . a storm passed through this afternoon and knocked power off for just a split second. But, that was enough to send gremlins through the network and re-zap those two 4-port network switches again. Bandwidth dropped to 6mbps instead of the normal 30mbps I overpay Comcast for. Also affected the network speed between my PC and the WDTV, of course. Anyway, I had to turn off the whole networked system and then do the turn-on sequencing to get things right. again.