I spotted that when I am using my iPhone to browse problems, if I'm connected to a wifi network, the game board renders ok. If I am using 3G, the board is brown (as opposed to yellow) and the grid is not visible. I can see the stones, make moves, but I can't see the grid.
After I searched a bit for the possible cause of the problem, I came across this post:http://stackoverflow.com/questions/3282 ... under-wifi
I realize it is not a problem cause directly by goproblems, but by the carrier, but maybe you can look into this and fix it.