Hammer grid problems

I have the Problem that i cant realy read the sizes of the brush that i want to set like inthe pic !

http://img14.imageshack.us/img14/3952/unbenanntqwo.png

What can i do ?

You’re using an AMD graphics card aren’t you? I can’t remember the resolvement for the issue but other FPers do.

Yep its AMD

Turn off aa in the catalyst settings i think.