Anyone have problems with the screen becoming unresponsive during use? Today I noticed while playing angry birds that the screen would randomly stop responding to touch. Then later I was filling out my daily time sheet in an excel spreadsheet and again it happened. I tried playing a different game tonight and again the same thing... It seems to be working fine at this particular moment as I type this, but one thing I noticed is the back was quite warm when I was experiencing the problem. Now it is cool to the touch. Anyone else have this problem?