I've purchased 3 Google Chromecasts with Google TV since October. I returned the first two because of what I thought were hardware defects. Now the third one is doing exactly the same as the first two did. Very basic setup on a bedroom TV with basic apps. Here's what happens every time:

1. Chromecast is set up successfully and the first 3 weeks or so all is good.

2. I try to watch TV and there are strange video artifacts (stripes, blocks on the home screen), also the home screen navigation stops working properly and I can't select 'Settings'.

3. No choice at this point but to re-boot by unplugging power.

4. Upon re-boot I get an immediate message that there is no WiFi connection. When I go to Settings and look at network connections the WiFi is active but I have "limited connectivity". Nothing works at this point. Even when I switch to other access points in my house I have "limited connectivity" and no internet.

I can re-set the device to factory defaults at this point, which fixes things, but in a few days the cycle repeats starting with step 2 above.

Seems obvious that I'm having issues with the devices themselves, but what's causing this over and over??? The Chromecasts are plugged directly into the TV, and directly into a power bar behind the TV. That's it.

Any advice or suggestions would be appreciated. There's obviously not much point in returning this for a 4th replacement. Why are these failing?