DISEASE CHARACTERISTICS: Histologically confirmed advanced stage IV malignant melanoma M1 All pathologic subtypes eligible Tridimensionally measurable disease At least 1 discreet easily accessible and measurable cutaneous or subcutaneous lesion of a volume no greater than 3 cm3 by physical examination using Vernier calipers Ulcerated or necrotic lesions may not serve as index lesion Not a candidate for curative surgical resection Visceral metastases, including brain lesions, eligible provided no rapidly progressive CNS metastases likely to result in death within 3 months

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Greater than 3 months Hematopoietic: Absolute neutrophil count at least 1,800/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9.0 g/dL Hepatic: BUN no greater than 1.5 times upper limit of normal (ULN) Bilirubin no greater than 1.5 times ULN Renal: Creatinine no greater than 1.8 mg/dL OR Creatinine clearance at least 70 mL/min Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 3 months after study No other clinically significant medical disease that is poorly controlled and/or expected to impact patient survival or that would preclude study therapy No significant cognitive impairment No serious active infection requiring intravenous antibiotic or antiviral therapy No clinical AIDS No primary immunodeficiencies No other concurrent active malignancy No history of sensitivity to ganciclovir or other antiviral drugs of this family No prior severe reaction to adenovirus or herpes virus infection (e.g., toxic epidermal necrolysis or Stevens-Johnson syndrome)

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biological response modifier therapy (e.g., interleukin-2, interferon) and recovered No prior gene therapy using adenoviral based vectors, chimeric adenoviral based vectors, HSV-tk or other thymidine kinase based therapy No concurrent biological response modifier therapy No other concurrent gene therapy including ribozyme and antisense based therapy Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas, melphalan, or mitomycin) and recovered No concurrent antineoplastic chemotherapy Endocrine therapy: Concurrent replacement or therapeutic corticosteroids allowed Radiotherapy: Prior radiotherapy allowed provided index lesion not within radiation field Recovered from prior radiotherapy No concurrent radiotherapy except for CNS metastases provided index lesion not within radiation field Surgery: See Disease Characteristics Recovered from prior surgery Other: No other concurrent ganciclovir, acyclovir, or similar antiviral drug No concurrent immunosuppressive therapy (e.g., organ allograft)