I checked the trace file..not much from there

ORA-01157: cannot identify/lock data file 18 - see DBWR trace file
ORA-01110: data file 18: '/oracle/oradata/POL1/NETRMS_UCR.dbf'
ORA-27037: unable to obtain file status
IBM AIX RISC System/6000 Error: 2: No such file or directory
Additional information: 3

Repetadily I am getting this in the trace file.

Thanks for the replies.