  We show that in D=2n+1 dimensions, when mass is negative and all angular
momenta are non-vanishing, Kerr and Kerr-AdS metrics describe smooth time
machines, with no curvature singularity. Turning off the angular momenta
appropriately can lead to static AdS solitons with negative mass. Setting zero
the cosmological constant yields a class of Ricci-flat K\"ahler metrics in D=2n
dimensions. We also show that Euclidean-signatured AdS solitons with negative
mass can also arise in odd dimensions. We then construct time machines in D=5
minimal gauged supergravity that carry only magnetic dipole charges. Turning
off the cosmological constant, the time machine becomes massless and
asymptotically flat. It can be described as a constant time bundle over the
Eguchi-Hanson instanton.
