Oracle startup error: "end-of-file on communication channel"
O/S-Error: (OS 665) The requested operation could
  not be completed due to a file system limitation


So the windows error 665 is the reason for the error an the error refers to file C:\ORADATAFILES\ORAPROD03\USERS03.DBF.What is the problem with the file? The following article discusses this error message:  What factors can lead to Win32 error 665 (file system limitation)?. If the reason is file fragmentation a patch is available. I know it is to late but maybe a restore will not be necessary in this situation.