Hello I see that the two files are différents: 1 - ntfs_original.sys is made with version 6.1.7600.16385 inside property we can see:(win7_rtm.090713-1255) 2 - ntfs_new.sys is made with version 6.1.7600.20575 inside property we can see: (win7_ldr.091113-1530) Weird! Ah looks like one of the hotfixes i injected into the install. http://support.micro....com/kb/976538/ Don't touch this one Didn you said you didnt made ANY changes, just created the iso? And now you say you integrated an update.. Weird! Sorry it seems that the folder i had for the contents of the W7 stuff had the hotfix injected into it, rather than using 7C, i did create this ISO back in feb, memory fails me.