to run ace from from file:/// url, you need to enable local XMLHttpRequests

firefox: from about:config set security.fileuri.strict_origin_policy=false

opera: opera:config#UserPrefs|AllowFileXMLHttpRequest

chrome: start it with --allow-file-access --allow-file-access-from-files flags

safari: Enable Develop menu (Safari->Preferences->Advanced->Show Develop menu in menu bar), then turn off local file restrictions (Develop->Disable Local File Restrictions)

ie: ?