ZBrushCentral

sculpt with each brush quickly will switch to the mask brush

a strange zbrush problem happened to me while I am working on my new computer ,
could you take a look at this 20 sec video please?

http://www.youtube.com/watch?v=BcCOnxnmi5M&feature=youtu.be
Without
pressing any key on the keyboard, My normal brush jumps to a mask brush by the
end of every stroke for a brief moment (please notice the weird flashing on the
top-left brush panel), and some times it will leave a mask on the model, do you
know what causes this?
The problem occurs while I am using both mouse and
tablet, so I think it is not the problem of the tablet driver…
My system is
windows7, with flickers turned off… I have tried reseting and reinstalling my
zbrush but it won’t work…

Do you guys have any idea how to fix
this?..O-O

Thanks a lot!