Nikon D5100 focusing issues - intermittent problem?

When this happens I thought I'd try to switch to manual on the lens, but I can't the toggle button will not budge. Also, I get either r08, r24, r200 showing up on the bottom right of the screen. My card was empty, lighting was great. I got the camera end of January, and all was well until the beginning of March. I reset the settings to the how they would have been when I first bought the camera, but this didn't help. I have read this a buffering thing, but why now and not before. I'm using the same card I always did. Just want to know if it's some setting or if I need to bring it to the doctor?

I don't find those error codes in your manual. The toggle button on the lens should easily toggle. You should get no error codes. Sounds like you have a problem with the lens. If it is a Nikon (Nikkor) lens, start your troubleshooting with Nikon and expect to send the lens in for repair.
http://www.nikonusa.com/...index.page