DISEASE CHARACTERISTICS: Histologically confirmed advanced solid malignancy with imaging evidence of progressive brain metastases Failed or refused surgery, whole brain radiotherapy, and/or stereotactic radiosurgery No lymphoma Systemic disease allowed (if uncontrolled, must be less life-threatening than brain metastases) Bidimensionally measurable brain disease by MRI Previously treated lesions must show progression and be measurable No known carcinomatous meningitis

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: More than 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 10 g/dL Hepatic: Bilirubin less than 1.5 times upper limit of normal (ULN) SGOT and SGPT no greater than 3 times ULN Alkaline phosphatase no greater than 3 times ULN Renal: Creatinine less than 1.5 times ULN BUN less than 1.5 times ULN Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No known HIV infection No other malignancy within the past 2 years except surgically cured carcinoma in situ of the cervix or basal cell or squamous cell carcinoma of the skin No other serious medical condition No acute infection treated with IV antibiotics No frequent vomiting or other medical condition that would interfere with oral medication intake (e.g., partial bowel obstruction)

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 2 weeks since prior biologic therapy or immunotherapy and recovered No concurrent growth factors administered for the purpose of continuing temozolomide No concurrent epoetin alfa Chemotherapy: Prior adjuvant chemotherapy allowed Prior chemotherapy for metastatic disease allowed At least 4 weeks since prior chemotherapy except vincristine (6 weeks for nitrosoureas or mitomycin) and recovered Endocrine therapy: Prior and concurrent steroids allowed if neurologically stable or improving Concurrent hormonal therapy allowed for stable breast cancer Radiotherapy: See Disease Characteristics At least 2 weeks since prior radiotherapy or interstitial brachytherapy (4 weeks for brain radiotherapy) and recovered No concurrent radiotherapy Surgery: See Disease Characteristics At least 1 week since prior surgery and recovered Other: At least 4 weeks since prior systemic therapy No other concurrent investigational agents