bootstrap.inc HTTP_HOST notice [#42876]

Using HEAD, I get the following when loading pages (includes header output using WS_Ping ProPack). The notice doesn't appear in browser output of firefox or IE or when I view the source of either. I don't know if this is something quirky about WS_Ping or WIn32 or what, but HTTP_HOST isn't defined in the init function (verified by var_dump($_SERVER); die; in conf_init()), even though it appears in a phpinfo(). Since the notice is so early, it hasn't been watchdog logged.

<code>
HTTP/1.1 200 OK
Date: Sat, 31 Dec 2005 16:54:49 GMT
Server: Apache/2.0.55 (Win32) DAV/2 PHP/5.1.1 SVN/1.2.3 mod_ssl/2.0.55 OpenSSL/0.9.8a
X-Powered-By: PHP/5.1.1
Set-Cookie: PHPSESSID=n3hqig1uk5nlhf29gfehj4nkt7; expires=Mon, 23 Jan 2006 20:28:09 GMT; path=/
Connection: close
Content-Type: text/html; charset=utf-8


Notice: Undefined index:  HTTP_HOST in E:\Web\dkn_portfolio\drupal\includes\bootstrap.inc on line 120
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
{remaining content cropped}