When did the web accelerator 'CACHEbox' and browser 'Internet Explorer' become compatible?
select t1.compatible_since_year from accelerator_compatible_browser as t1 join browser as t2 on t1.browser_id = t2.id join web_client_accelerator as t3 on t1.accelerator_id = t3.id where t3.name = 'CACHEbox' and t2.name = 'Internet Explorer'