NFS_MillDisplay0.dat is the display map file that the wizard uses. If you are having a crash that leaves that file open then a later startup will fail. Are you trying to run 2 copies of the wizard? Did you open one copy and 'loose' it behind another window?
I dont think a re-install should do much, but a re-boot would clear any open files. After a crash its hard to say what was left open or locked. A re-boot clears all.