[Snow]

Thanks so much all for your input. Isis is 2 years old and she has never had problems with other dogs until about approx 6mos ago - she was in beginner, intermediate, and advanced classes at Petsmart, the classes were pretty big with differing types of dogs. We used to take her to dogparks and Petsmart regularly until she started turning into Cujo (as Angelbunny described it). She seems to be particularly aggressive if the other dog starts barking - which is usually the little yappy ones.
Heather, I will most definitely be giving you a call - I really need some help and am worried that I won't be able to correct this behaviour - pretty upset about it, esp since I am pretty sure it is my fault, perhaps even just my ignorance! Thanks so very much for offering, it means alot.

I'm pretty frustrated with trainers right now as well, esp since (as you noted, Gina,) they should be there to help...
Thanks again guys and i'll keep you posted on her progress,
Jen