HTC One M8 Keeps coming on to a multi-colored screen

My phone has been doing some wierd stuff.  It flashes back and forth to a multi-colored screen. It will also randomly go in to "car" mode. I have never turned car mode on before. It does not do a "re-start" which I have seen in other posts, but it keeps turning in to what appears to be a "lock screen" but when I tap it, it goes away. It has doen this before, but then it just stopped. Now it makes it hard for me to type on it as it will randomly appear when I'm trying to make a call or type a text. Sometimes over and over. Is this a reboot issue or something else?

thanks,

jw