  We show that the combination of a weak magnetic propeller and accretion disc
resonances can effectively halt accretion in short period cataclysmic variables
for large fractions of their lifetimes. This may help to explain the
discrepancy between the observed and predicted orbital period distributions of
cataclysmic variables at short periods. Orbital resonances cause the disc to
become eccentric, allowing material to fall back onto the donor star or out of
the system. A weak magnetic field on a rapidly spinning primary star propels
disc material outwards, allowing it to access these resonances. Numerical and
analytic calculations show that this state can be long lived (~10^11 yr). This
is because the magnetic propeller is required only to maintain access to the
resonances, and not to push matter out of the Roche lobe, so that the spin down
time-scale is much longer than for a classical propeller model.
