If you have installed other releases of Hydra, system variables PATH and LD_LIBRARY_PATH may contain several values (old and new) and old values will be included first. When runtime tries to found dynamic libraries it looks for it refering to path defined in LD_LIBRARY_PATH and finds 'old' version first.

To fix it log in as user that Hydra runs from and look at environment variable LD_LIBRARY_PATH. Edit your $HYDRA_DIR/environ file to make LD_LIBRARY_PATH start with $HYDRA_DIR/lib and PATH start with $HYDRA_DIR/bin.