Cuelists w/ blue/gray stripes and less control

I was doing a show yesterday using my Nano Hog 4 for live busking. I have many pages of Lists, some that repeat the same list obviously. What I noticed is about 1/2 way thru the night, some of the playbacks kept getting these blue/gray stripes where the name of the List usually is on the page. When this happened I no longer had the ability to release anything including Pig+Release. I also was no longer able to hit the play button and have it skip to the next cue in the sequence but I could hit the back button. The top and bottom indicator LED's were also flashing constantly. Not a show stopper but definitely inhibitive. I can't find anything in the manual to point me in the right direction. What is that, how did I accidentally make that happen and how do I correct it next time it decides to do that?