I have been having the stream loading issue for the past 3 or 4 days as well. Worked great for years apart from the time about a year ago (maybe?) when many people were having this issue and someone stumbled upon the fact that it may have been connected to too many items in your netflix instant queue. Tried that this time, plus rebooting, checking router, delete Netf. channel, reboot, re-add, etc. No luck.
Interestingly, this time I'm currently having an issue with my Amazon instant stream as well. It plays a few seconds and then tells me that 'this program is temporarily unavailable'.
Any suggestions or help would be appreciated. My roku has no value without Netflix.
Sounds a bit like the DNS you are usng is not providing a good route to your Netflix and/or Amazon CDN.
Try changing your primary DNS to Google DNS ( 188.8.131.52 ) or OpenDNS ( 184.108.40.206 ) or Verizon/GTE DNS ( 220.127.116.11 ). It is simple to change and you can always change back if it does not help.
Also, if your Roku is running wireless and you have one that can go wired temporarily run a cable and test it wired to see if it is a wireless issue. Also try a different ch for wireless as something could be interfering on the current ch even if it is "auto". Channel 11 is often recommended but others like 6 are reasonable to be tried. BTW: an "Excellent" signal reading is nearly meaningless as it only really reflects signal strength and most interference issues will not be indicated in Roku's report.
Also a slight relocation of the Roku can often reduce the effect of any interference.