I flashed a custom Rom using Odin 4.43 Multi Downloader
Do you still have the touchwiz rom in your external sd-card? If it's still there, do this steps in cmw:
select "wipe data / factory reset"
go to "mounts & storage" and format /system. This is extremely important!
under the same menu, format /sdcard0 (be careful NOT to format /sdcard1 by mistake)