Means this a previous installation has already created it
Not from any of our software. The error was surely created by another installer and, as I've said, our installer FIRST checks for syntax and THEN modifies it, otherwise it stops with the message you saw, and doesn't continue copying files.
The grafic problems have been fixed meanwhile.
Because, if you reinstalled it again, it might have fixed the corrupted EXE.XML by itself.
This damn installation has change my grafic settings. Thats impudent.
The installation doesn't change your graphic settings.
It's just that, the FIRST time you ran the installer, because your file was corrupted, it didn't copied all the textures, that's why you didn't see textures. The second install, either because you fixed the file or because the installer was able to fix it by itself, the installation obviously complete, so the scenery now appears correct.