I would try to set in the Flag Box "-v 2 -w 256" or even "-v 4 -w 236".

For further help you should check if anything graphical runs in background (video,music etc playing). Very bad on GPU usuage is the always loved Flash(tm) plugin of your browser.
Open your Task Manager and check for CPU Load.

otherwise i can suggest using cgminer (find it on http://ck.kolivas.org/apps/cgminer)
there is a very easy to understand manual for configurating. Another big advantage is the very well output of the app. So Error Detection is easier.
use --debug for a lot of output.

my TipBox:):  1Nrs2jTZddhhZEbawR27ambdiz7FnvdBH9