Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain. Cover to keep warm and set aside.
Meanwhile heat oil in a wok or frypan over high heat. Saute chicken and onion 3 minutes. Add yellow pepper and continue cooking until chicken is no longer pink and vegetables are crisp-tender. Add garlic, chicken stock, sherry, salt and pepper. Cook just until hot. Blend in cream cheese and heat through. Do not allow to boil.