There are two phases to this study, Phase I and Phase II. If you are assigned to Phase 1, you will receive treatment with imatinib mesylate and paclitaxel. Phase 1 will study 3 different doses of imatinib mesylate in combination with a fixed dose of paclitaxel. The Phase I part of the study will help researchers learn the most effective dose of imatinib mesylate to be used in combination with paclitaxel. All participants in Phase 1 will receive one of three doses of imatinib mesylate to be given with a standard dose of paclitaxel. You will be assigned to a specific dose level based on the number of participants treated at the time of your enrollment.