Paclitaxel is an active antitumor agent that has demonstrated a broad range of activity in preclinical and clinical studies. The optimal dose and schedule has not yet been determined in either adults or children. The objective of this trial is to determine the maximum tolerated dose and the toxicities of paclitaxel given as a short hour infusion in children with refractory malignancy. In addition, the pharmacokinetics of paclitaxel given in this way will be studied and both model-dependent and model-independent parameters will be determined.