Yeah, its over heating. I made a bunch of those mistakes when I first got mine. Here are a few tips:
First I'm assuming that you are running mono-bridged into a four ohm load. Next, make sure the "suck switch" (ultra low) is disengaged. Gain should be high enough that you get the red clip light fairly often (don't worry, its ok) and don't use the compressor. Bass should be around 12 to one o'clock, mids boosted about two-ish with the selector at 1, 2, or 3 and, treble at noon. Bright and ultra high to taste.
Don't worry about the graphic just yet. You can figure that one out later. However, I don't recommend a smiley face unless you are in your living room. Also, I would use it to slightly cut the ultra lows.
Now, you probably won't have to crank the master that much to get exceptional volume. When I had mine set like this using a 610 cab 12 o'clock on the master just flat out hurt.
Hope this helps. The other idea is that if it is in a rack, take it out. That fan exhaust is easy to block.