  The far-from-equilibrium low-temperature dynamics of ultra-thin magnetic
films is analyzed by using Monte Carlo numerical simulations on a two
dimensional Ising model with competing exchange ($J_0$) and dipolar ($J_d$)
interactions. In particular, we focus our attention on the low temperature
region of the $(\delta,T)$ phase diagram (where $\delta= J_0/J_d$) for the
range of values of $\delta$ where striped phases with widths $h=1$ ($h1$) and
$h=2$ ($h2$) are present. The presence of metastable states of the phase $h2$
in the region where the phase $h1$ is the thermodynamically stable one and
viceversa was established recently. In this work we show that the presence of
these metastable states appears as a blocking mechanism that slows the dynamics
of magnetic domains growth when the system is quenched from a high temperature
state to a low temperature state in the region of metastability.
