Part 3: During Part 3 of the study, HCV gentoype 1-infected patients who are treatment-naive (have not been treated for HCV) will be enrolled. Up to 75 patients (3 groups of 25) will be dosed for 28 days with RO5024048, PEG-IFN, and RBV. The first dose of RO5024048 to be given in Part 3 will be 500 mg BID, the second dose will be 1500 mg BID, and the third group will be 1000 mg BID. Standard doses of PEG-IFN and RBV will be used during Part 3. Doses of PEG-IFN and RBV will be modified if necessary.