Dynamics simulations keep failing with unknown error message.

271758831 intermediate file n1ac-5-constr_bond_angles.monitor
1271758831 intermediate file n1ac-5-constr_bond_angles_opt.summ
1271758831 intermediate file n1ac-5-constr_bond_angles.car
1271758836 message SCF converged
1271758836 progress 0
1271758841 message SCF converged
1271758841 intermediate file n1ac-5-constr_bond_angles.monitor
1271758841 intermediate file n1ac-5-constr_bond_angles_opt.summ
1271758841 intermediate file n1ac-5-constr_bond_angles.car
1271758846 progress 0
1271758847 progress 100
1271758847 message error DMol terminated with unknown error status.
1271758847 status new failure-completed

I have tried making constrained dynamics, but get always the same error. Any help?