$re = '/[^\[]+\[(?<timestamp>[^\]]+)\].*\n.*\n(?<description>.*)\n\s+\[(?<eventtype>\w+)\D+(?<eventid>\d+)\]/';
$str = '<DIV id="A">[Jan 22 20h39:02.924] - <a href="javascript://" onClick="toggle(this)">Disconnected from server \'SERVER102\'</a>
<DIV id="B"><UL>
Disconnected from server SERVER102. Reason: Initiated by the Server application<P>
[Error event 8000]
</P>
</UL><HR></DIV>
</DIV>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php