networking problem

I am new to this forum, but I have a question that has been bugging me lately. I have a mini and a macbook and I had them sharing files successfully for about 6 months. then I installed parallels desktop on the macbook and now, although they show up in each other's shared network folder, they never seem to be able to connect so that I can share files. But I have been able to share itunes libraries?

any hints as to what it might be?