I purchased the D810 a few months ago and this is the second time that it has locked up on me while shooting sports. The first time I took the lens off and put it back on and it worked fine. This time I was not so lucky. I removed the lens, replaced the lens, tried a different lens and took the battery out. None of the buttons or dials would respond. I tried it the next day and it now works fine. Has this happened to anyone else? Am I possibly hitting some button without realizing it?