Q: I accidentally cooked 1 oz of milk with 1 oz of meat, then that mixture accidentally fell into a pot on the stove with 100 oz of meat. What is the status of the food?

A: The whole thing is trief (unkosher). One might think this is kosher because of bitul b'shishim (nullification in 60) because there is more than 60 times as much meat as milk, since there is 1 oz of milk and over 100 oz of meat in this final mixture (see Halacha of the Month - Tishrei 99). However it does not work that way here because of a concept called 'chaticha naaseh nevaila'. What happens is that the 1 oz of milk and the original 1 oz of meat combine to form one 2 oz entity of trief, so in order for bitul b'shishim to work you need 60 times as much as this new 2 oz entity (or 120 oz), not just 60 times the 1 oz of milk. Therefore 100 oz will not be enough to nullify this.

A: No. Bitul b'shishim only works when the mixing was accidental. You cannot intentionally mix milk and meat in a 60:1 ratio with the purpose of having bitul b'shishim. Therefore the food in the above case must be discarded.

Q: What happens to the pot in the above example?

A: It needs to be kashered.