It also seems to me like she has no understanding of what the theory actually says, that she was just told not to like it by her pastor and is repeating whatever silly argument the pastor used that she happens to remember.
While the odds of changing that are slim, you might want to try as Paul C. said, starting with the very basic of the theory and correct her misconception. If she contradict you at that point, it probably going to be with misconception. Correct them patiently. If she 'jump the shark' and attack you with standard creationist BS, ask her to be patient. You need, after all, to get the basics of what you are discussing clear before debating it's validity. If she gets annoyed at you 'avoiding the debate' point to her sig and mention how that seems to indicate at least to misconception about Evolution and that you feel it is necessary to make the theory clear before moving the conversation further. Be firm but patient.
Once you are done with explaining the theory, start showing evidences for it. ERVs are great example.
You can also answer to her BS (do you know
talk origin? This website is invaluable to answer).
You seem to be polite and patient, and these are great qualities.
It might not help convincing her (although, it won't hurt) it will help convince people reading the argument that have not yet drank the cool-aid as much.
She does not seem to know much about the subject (considering her refusal to give arguments), or care enough to educate herself, even by reading creationist literature.
So, odds are high that either she will parrot the same BS time and time over and refuse your offer of dialogue, or she will stop participating altogether. In either case you will appear victorious.