Group 3 (select solid tumor patients): Patients receive oral isotretinoin twice daily on days 1-14. Patients also receive SAHA once daily on days 1-28 OR once on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22, 24, and 26. Treatment repeats every 28 days for up to 12 courses in the absence of disease progression or unacceptable toxicity.The MTD of SAHA is determined as in group 1. An additional 6 patients may be treated at the MTD.