LNAV Goes In Circles

This has happened to me a few times before, but most recently it was a 777. There was a somewhat sharp turn in my flight path and LNAV started turning, but when it was lined up, it kept on turning. It kept going in circles for over 15 minutes, and it would have kept on going if I didn’t stop it. My current solution is to select a heading and name use HDG select, then switch back to LNAV after a few minutes. I was at 35,000 FT and M.84.

Ok I will get that asap. Thanks.