Use the /s flag to have the '.' also apply to new line characters, or just check for new line characters explicitly - usually '[\n\r]'. I haven't yet read it myself, but do check out more info on the PCRE library at http://www.pcre.org/pcre.txt
Careful how you form your pattern though - long input strings with newlines mixed with misunderstood patterns can cause unexplained script failures and connection resets.
In your case, PCRE functions don't seem to be needed here, and could cause unexpected results anyway. If you're just looking to extract contents of a single table on a page, why not just do the most basic...
$start = stripos($input, "<table>");
$end = stripos($input, "</table>", $start);
$my_table = substr($input, $start, $end);