How long have you had this? did you have these problems before the recent updates - back in 11.29 or 11.26? The mail-400 is known to have issues, but usually it's getting it to work at all, not issues with compatibility.
Did you try 32-bits rendering? that the only setting I have heard of that can help with garbage.
I looked at the specs for your device - is this it? http://www.pandawill.com/yinlips-ydpg18 ... 54352.html
that's a decent LOOKING device. is that it? the specs are decent too. 1 ghz. mali-400. too bad it's only 512 megs ram though. price is nice. I would tell you to try to overclock it - cpu or gpu, or both - but if your issue is hardware, that will just make it worse. I know some people that had similar issues that used chainfire3d which allowed them to lower some gfx resolution and made the compatibility work - got rid of garbage. warning, I also read about someone that installed chainfire3d without reading about supported devices and he had to reflash his device.
Please see my opengl thread, it has tons of information. I'm going to update that thread with the chainfire story. Also, I would love you fto post your experience in my thread.
 I went back and looked at the posts in my thread. the people that did the chainfire3d trick had different GPUs. however, you'll see from that thread that the two different people that left screenshots had issues similar to yours. so - you can try chainfire3d if you want. be careful though.
[edit2] I checked agin - the secnond issue was a galaxy s2, which may be a mail-400 - which may be about the same as your issue. He tried the chainfire3d which fixed the issue - but caused other issues. again - check the opengl thread.
see my signature for a link to my opengl thread.