I was afraid that might happen. Are you using FF7 through Steam or the PC re-release? If so, have a read of this first:
http://forums.qhimm.com/index.php?topic=14408.0There was a tool kicking around to convert the PC re-release into the 'old' 1998 version but I'm not sure how functional that tool was or if it'd even be compatible with the Steam release at all (there're three versions; the original 1998, the re-release that came out on the Square-Enix store, and now this Steam version).
You might want to try running Bootleg to convert the game into the 'old' version (which makes it compatible with most mods). It's a hefty download, and you'll lose Cloud saves (the game's saves take up next to nothing in space) and 'achievements' (if they can be called that) but the game will become compatible with mods. Hopefully.
http://forums.qhimm.com/index.php?topic=13212.0I saw later on this Bootleg thread, on p43, that it might be necessary to relocate your Steam files for the Bootleg install to D:\Games\Steam but that it might be possible to just put the FF7 folder in D:\Games instead (rather than moving the entire Steam directory) and then directing the bootleg installer at that instead.
You could maybe try taking the field folder out of the Steam FF7 Data folder, putting it on the desktop, patching it there, and then putting it back in but I doubt it'd work. Also, make sure to run the patch with administrator privileges; if it doesn't have that, it'll likely be blocked because it's trying to make changes to files inside Program folders.