DISEASE CHARACTERISTICS:

• Histologically confirmed refractory solid tumor and/or lymphoma
• No brain metastases or primary CNS malignancies

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• More than 3 months

Hematopoietic:

• Granulocyte count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin normal
• ALT and AST less than 2.5 times normal

Renal:

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

Cardiovascular:

• No unstable or newly diagnosed angina pectoris
• No myocardial infarction within the past 6 months
• No New York Heart Association class II, III, or IV congestive heart failure

Pulmonary:

• No chronic obstructive lung disease requiring oxygen therapy

Other:

• No uncontrolled seizures
• No concurrent acute critical illness
• No serious untreated infection
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 2 months after study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 4 weeks since prior biologic therapy

Chemotherapy:

• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas, mitomycin, or carboplatin)
• No concurrent cytotoxic chemotherapy

Endocrine therapy:

• At least 4 weeks since prior hormonal therapy
• Concurrent luteinizing hormone-releasing hormone agonist required in patients with prostate cancer unless prior orchiectomy has been performed

Radiotherapy:

• At least 4 weeks since prior radiotherapy

Surgery:

• See Endocrine therapy
• Prior surgery allowed

Other:

• Recovered from prior therapy
• No concurrent anticonvulsants (e.g., phenobarbital, phenytoin, or carbamazepine)
• No concurrent rifampin
• No concurrent grapefruit juice