Does anyone know how to remap keys. I am using keyboard and mouse. Rather use arrow keys to move.

everytime I try to run, i get error message "DOOM3 has stopped working" then it tells me "DEP has stopped DOOM3". I have followed other in structions on ixing DEP error, still not working. Even copied to shortcut and still wont work. Can someone help me, need another way to get this game running. or am i to wait for an update to fix problem?