DISEASE CHARACTERISTICS:

• Histologically confirmed advanced solid tumor that is refractory to standard therapy or for which no standard therapy exists
• No uncontrolled brain metastases, including symptomatic lesions or lesions requiring treatment (e.g., glucocorticoids and/or anticonvulsants)

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• At least 12 weeks

Hematopoietic:

• WBC at least 3,000/mm^3
• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3
• Hemoglobin at least 9 g/dL

Hepatic:

• Bilirubin no greater than 1.5 mg/dL
• AST and ALT no greater than 2.5 times upper limit of normal (5 times ULN if liver metastases present)

Renal:

• Creatinine no greater than 1.5 mg/dL OR
• Creatinine clearance at least 60 mL/min

Other:

• No active infections
• No other serious concurrent systemic disorders that would preclude study participation
• No other malignancy
• No prior hypersensitivity to sulfonamide-based drugs, nonsteroidal anti-inflammatory drugs, or fluorouracil
• No documented dihydropyrimidine dehydrogenase deficiency
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No concurrent immunotherapy

Chemotherapy:

• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered

Endocrine therapy:

• See Disease Characteristics
• No concurrent hormonal therapy

Radiotherapy:

• At least 28 days since prior radiotherapy
• No concurrent radiotherapy

Surgery:

• Not specified

Other:

• At least 4 weeks since prior investigational agents
• No other concurrent experimental medications
• No concurrent drugs known to induce cytochrome P450 3A4 (e.g., rifampin, phenytoin, carbamazepine, or barbiturates)