  We study the effects of light-cone fluctuations on the renormalized
zero-point energy associated with a free massless scalar field in the presence
of boundaries. In order to simulate light-cone fluctuations we introduce a
space-time dependent random coefficient in the Klein-Gordon operator. We assume
that the field is defined in a domain with one confined direction. For
simplicity, we choose the symmetric case of two parallel plates separated by a
distance $a$. The correction to the renormalized vacuum energy density between
the plates goes as $1/a^{8}$ instead of the usual $1/a^{4}$ dependence for the
free case. In turn we also show that light-cone fluctuations break down the
vacuum pressure homogeneity between the plates.
