I'm also having the same issue
(Also im a newbie this was my first attempt at any flashing etc.)
then installed Jelly Bread v5.0
was ok for a while and working but then i wanted to play with other ROMS (in this case i now wanted to try cm-10.1.4-GT-S5660-gio++.zip)
I enter recovery, wipe data/factory reset, wipe cache, wipe dalvik cache, wipe batt stats
Then install cm-10.1.4-GT-S5660-gio++.zip
Then it hung for 35mins at loading blue circle screen.
I then took battery out and enter recovery, and attempt to wipe data/fatory reset and it says:
E:format_volume: make_extf4fs failed on /dev/block/stl13
E:format_volume: make_extf4fs failed on /dev/block/mmcblk0p2
Formatting /sdcard/ .android secure...
Data wipe complete
Also i cant wipe dalvik cache it just does nothing blinks 1 second then back to menu.
Anyone know what i can do to fix this please?
Thanks for any help in advance.