Solution tested for EST (GMT -5) on Windows
In upload/include/class.format.php function date(), change:
return date($format,($gmtimestamp+($offset*3600)));
to:
return date($format,($gmtimestamp-($offset*3600)));
$offset is +5 for EST here, code assumes it will be -5. Note: not tested for timezones with a positive offset from GMT or other OSs, caveat emptor.
Best,
RJ Herrick