DISEASE CHARACTERISTICS:

• Histologically confirmed malignant melanoma

  • Any primary tumor site

• Stage IV disease

  • CNS metastases allowed
• Measurable disease, defined as at least 1 lesion that can be accurately measured in at least 1 dimension as ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan

• Must have had at least 1 prior systemic therapy

  • Patients with no prior systemic therapy are eligible provided they are not candidates for high-dose interleukin-2

PATIENT CHARACTERISTICS:

• ECOG performance status 0, 1, or 2
• Creatinine < 2 mg/dL OR creatinine clearance > 50 mL/min
• Calcium < 10.5 mg/dL
• Phosphorus < 4.3 mg/dL
• Bilirubin normal
• Platelet count > 100,000/mm^3
• WBC > 3,500/mm^3
• Life expectancy ≥ 4 months
• No known HIV positivity
• No evidence of active infection requiring antibiotic therapy
• No other malignancy within the past 5 years except surgically resected basal cell or squamous cell skin cancer
• No significant medical disease which, in the opinion of the investigator, may interfere with study completion
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Recovered from all toxic effects of prior therapy
• More than 4 weeks since prior and no concurrent radiotherapy, chemotherapy, or immunotherapy
• No prior temozolomide or dacarbazine
• No investigational agent within 4 weeks prior to study entry
• No concurrent magnesium-containing antacids, digitalis, bile-resin binding drugs, or calcium supplements