PRIMARY OBJECTIVES: I. Describe the 2-months progression free rate on vorinostat 800mg/day x 3 in combination with 5-FU/L V every 2 weeks. (Arm I) II. Describe the 2-months progression free rate on vorinostat 1400mg/day x 3 in combination with 5-FU/L V every 2 weeks. (Arm II) SECONDARY OBJECTIVES: I. Describe the response rate on Arm 1 and Arm 2 of the study. II. Estimate the median progression free survival on both arms of the study. III. Describe the overall survival on Arm 1 and Arm 2 of the study. IV. Describe the toxicities on Arm 1 and Arm 2 of the study. V. Describe vorinostat pharmacokinetics on Arm 1 and Arm 2 of the study. VI. Describe 5-FU steady state pharmacokinetics on Arm 1 and Arm 2 of the study. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive low-dose oral vorinostat once daily on days 1-3, leucovorin calcium IV over 2 hours on day 2, and fluorouracil IV over 46 hours on days 2 and 3. Courses repeat every 2 weeks in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive high-dose oral vorinostat once daily on days 1-3 and leucovorin calcium and fluorouracil as in arm I. Courses repeat every 2 weeks in the absence of disease progression or unacceptable toxicity. After completion of study therapy, patients are followed up for 30 days and then every 3 months.