DISEASE CHARACTERISTICS: Histologically proven metastatic or unresectable solid tumor for which no standard or curative therapy exists No CNS metastases

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) AST no greater than 5 times ULN Renal: Creatinine normal OR Creatinine clearance at least 60 mL/min Cardiovascular: No symptomatic congestive heart failure No unstable angina pectoris No cardiac arrhythmias No New York Heart Association class III or IV heart disease Neurologic: No peripheral neuropathy grade 2 or greater No uncontrolled seizure disorders Other: Not pregnant or nursing Fertile patients must use effective contraception No uncontrolled concurrent illness No active infection No history of allergy to platinum compounds, irinotecan, antiemetics, or antidiarrheals

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy At least 4 weeks since prior biologic therapy No concurrent immunotherapy Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks since nitrosoureas or mitomycin) and recovered No greater than 3 prior chemotherapy regimens for metastatic disease No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior pelvic radiotherapy At least 4 weeks since other prior radiotherapy No prior radiotherapy to greater than 25% of bone marrow No concurrent radiotherapy Surgery: Not specified Other: No concurrent antiretroviral therapy for HIV positive patients