I receive the same error message:
HDF_ERROR trying to use HDF output file
+Time Window: 23DEC2009 0130 28DEC2009; ITER= 0
The error arose just before the end of an unsteady flow 1d/2D long simulation.
No numerical errors was showed in 'Computation Messages' window relative to hydraulics computations in 1d or 2D domain.
Many plans based on the same model structure run correctly...
At the moment I can't fix the error