OBJECTIVES: I. Determine the maximum tolerated dose of oral carbendazim in patients with advanced solid tumors. II. Determine the qualitative and quantitative toxic effects of oral carbendazim in these patients. III. Characterize the pharmacokinetic profile of oral carbendazim in these patients. IV. Assess the recommended dose of oral carbendazim to be used in phase II studies. V. Determine preliminary evidence of antitumor activity of this regimen in these patients.