ick. I have not had that happen.
I was given very old lard from a neighbor cleaning out her freezer (she gave it to me for soap). For kicks, I bottled some of it in my pressure canner and stuck it in my basement food storage room. Some of it accidentally got left in the garage all summer after a soap making session; I found that about 6 months later and it looked and smelled fine, so I soaped with it.
so, I guess my question would be - where did you get it? was it cleaned and lendered properly? did you buy it at the store where they have to put in preservatives, etc?