assert failure... again

[TavAkuma]

sorry for bothering with such old things, but sometimes my mugen crashes and pop up the message "assert failure in spr-lib.c line 560" and i still don't know why it happens, so... my question is: what the hell means that message?!!! and how can i correct what's wrong? please help and thanks 

[Scar]

That usually happens when you delete a sprite that is being shared somewhere else in the sff.