DISEASE CHARACTERISTICS:

• Histologically confirmed solid tumor, meeting 1 of the following criteria:

  • Failed standard therapy and subsequent line therapy
  • Disease for which no standard therapy exists
• Any number of prior therapies are allowed provided standard treatment options have either been exhausted or are unable to be administered, in the opinion of the treating physician

• Measurable or nonmeasurable disease

  • Measurable disease is defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by CT scan or ≥ 10 mm by spiral CT scan

  • Nonmeasurable disease is defined as all other lesions, including small lesions (< 20 mm by conventional techniques or < 10 mm by spiral CT scan) and truly nonmeasurable lesions, including the following:

    • Bone lesions
    • Leptomeningeal disease
    • Ascites
    • Pleural or pericardial effusion
    • Lymphangitis cutis/pulmonis
    • Abdominal masses that are not confirmed and followed by imaging techniques
    • Cystic lesions

• Brain metastases allowed provided both of the following are true:

  • Patient has undergone resection and/or radiotherapy and does not require steroids
  • No evidence of disease progression by CT scan or MRI at least 4 weeks after completion of steroids, surgery, and/or radiotherapy

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2
• Absolute neutrophil count ≥ 1,500/mm³
• Platelet count ≥ 100,000/mm³
• Hemoglobin ≥ 8.5 g/dL (epoetin alfa supplementation allowed)
• Bilirubin ≤ 1.5 times upper limit of normal (ULN) (except if due to Gilbert's syndrome)
• AST and ALT ≤ 2.5 times ULN
• Creatinine < 1.5 times ULN
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective barrier method contraception during and for 3 months after completion of study treatment
• Must be able to tolerate oral intake for the administration of imatinib mesylate and capecitabine
• No active serious infections
• No known allergy or hypersensitivity to study drugs or their formulation
• No comorbidity or condition which, in the opinion of the investigator, would preclude study participation
• No other primary malignancy within the past 5 years except basal cell skin cancer, cervical carcinoma in situ, or another primary malignancy that is not currently clinically significant or requires active intervention
• No other malignant disease
• No New York Heart Association class III-IV cardiac disease
• No congestive heart failure
• No myocardial infarction within the past 6 months
• No known chronic liver disease (e.g., chronic active hepatitis or cirrhosis)
• No known HIV infection

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Prior treatment with gemcitabine hydrochloride, capecitabine, or imatinib mesylate allowed provided all three drugs were not used in combination simultaneously
• Prior radiotherapy allowed provided the lesion treated is not used to assess response and has not demonstrated progression after treatment
• At least 2 weeks since prior radiotherapy
• More than 2 weeks since prior major surgery
• At least 4 weeks since prior systemic therapy (6 weeks for nitrosoureas) and recovered
• More than 4 weeks since prior packed red blood cell transfusions
• No prior radiotherapy to ≥ 25% of the bone marrow

• No concurrent anticoagulation therapy with warfarin

  • Therapeutic anticoagulation with low-molecular weight heparin or heparin allowed
  • Mini-dose warfarin (e.g., 1 mg/day) for prophylaxis of central venous catheter thrombosis allowed at the discretion of the treating physician
• No other concurrent anticancer agents, including chemotherapy and biologic agents
• No other concurrent investigational drugs
• No concurrent routine systemic corticosteroid therapy (corticosteroid therapy may only be administered after consultation with the principal investigator)
• Concurrent bisphosphonate therapy allowed for skeletal metastases provided therapy is started before study entry