I normally do this anyway--the tape icon flashes. It's a way to force the system to recognize that it's an electronic tape, not a normal one. This method hasn't fixed it yet, unless you mean to just keep holding it for a long while. (I haven't actively tried to use this to make it disappear, I just know that I've done this several times and the message still appears.)
Everything on the radio/tape player/CD player works as expected, it's only the display that's messed up. My aux power fuse was blown, so while I had the fuseboxes open today I checked the display fuses and everything was fine. My dad knows cars and he said that the aux power fuse may somehow fix the display, but I personally doubt that it'll do anything. I'll be driving it long-distance tomorrow, so I can report back then with regard to this in particular.