Same problem, and the "solution" is temporary. One to three days later, the problem returns, with YouTube the only channel not launching.
We used a Roku 2, not a smart TV, until last week when after YT froze again, I picked up a Roku 3 on Craigslist. The remote that came with it appeared to have had little use, and when I tested the new Roku at home, it worked perfectly. I thought this problem was behind me.
Until just now, when again YouTube failed to open, and again I fixed it by remove/install/sign in. PITA, right?
What do we have so far?
1) It's not my Roku box. Another box has the same problem. Also, everything else about the Roku box works. On the old Roku 2 box, I tried the complete reset and system update. YT worked afterward, but only for a few days.
2) It's not the TV or the remote. They work fine for everything else.
Roku Support: help, please. Thanks. My wife is no longer impressed with my ability to get YT working. 🙂