[20:14:52.61] C:\test>dir 834245.masks
 Volume in drive C has no label.
 Volume Serial Number is 8C78-4B42

 Directory of C:\test

18/04/2010  01:02     2,412,431,484 834245.masks
               1 File(s)  2,412,431,484 bytes
               0 Dir(s)  296,257,802,240 bytes free

[20:16:19.67] C:\test>perl -ne "s/\x00\x42\x00\x11/\x00\x42\x00\xf0/sg" 834245.masks >junk.dat

[20:16:55.62] C:\test>