How to root Acer Iconia A100?
I had similar problems with 4.0.3 and 4.1, but I fixed it with king root (note the lack of an 'o' after 'king'). It is one of those one click root methods, but it has served me well, and always resides in my toolkit.

Download link (XDA Developers) : http://forum.xda-developers.com/devdb/project/dl/?id=14576&amp;task=get