  We demonstrate that generically an accretion disk around a compact object
could have a new type of instability in that the accretion flow need not be
symmetric with respect to the equatorial plane even when matter is supplied
symmetrically farther out. We find that this behaviour is mainly due to
interaction of outgoing matter bounced off the centrifugal barrier and the
incoming accretion. We believe that X-ray variability could be developed by
this instability.
