  Searching for space/time noncommutativity we reconsider open strings in a
constant background electric field. The main difference between this situation
and its magnetic counterpart is that here there is a critical electric field
beyond which the theory does not make sense. We show that this critical field
prevents us from finding a limit in which the theory becomes a field theory on
a noncommutative spacetime. However, an appropriate limit toward the critical
field leads to a novel noncritical string theory on a noncommutative spacetime.
