afni.nimh.nih.gov

Perhaps another point to note is that the statistics output
from 3dANOVA are based on the degrees of freedom. If you
don't have very many subjects, it is likely all of your stats
will be smaller.

How many subjects do you have?

While one might expect 5% of 'noise' voxels to exceed p=0.05,
that assumes having enough subjects to make the distribution
basically normal.

Or am I off on this, Gang?

- rick