mini box

lately ive been having issues...i cant change channels...for instance,i'll punch in,say,channel 15...it'll display 15 in the upper right of the screen but the channel wont change and the graphic stays up there forever..also it stops showing me whats on as i flip through (program unavailable is all i'll get)...ive tried powering off and unplugging everything and that'll fix it for a short time but it starts doing it again. also ive noticed the box seems hot even when the tv isnt on....