[pstricks] Undefined control sequence \@zero in pstricks-add

[Ryan Haynes]

Hi, I am new to pstricks and I'm trying to get pstricks-add to work.
I'm using MikTeX 2.8. I have been getting the following error:

'pstricks-add' v3.38, 2009/12/13 (dr,hv)
! Undefined control sequence.
\resetOptions ->\@zero
  =0\def \pst at linetype {0}\pstScalePoints (1,1){}{}\pss...
l.1901 \resetOptions

Any suggestions on which package defines the \@zero macro? I've
allowed MikTeX to download all the versions automatically from CTAN,
but maybe it downloaded an incompatible version of something.

Thanks,
Ryan