update failure 0x80072EFD over proxy

in the envoirement, the proxyserver is the only computer that is allowed to
connect to the internet (firewall-rule 80 / 443).
on the xp client there is an automatic proxy configuration script
(proxy.pac) for internetconnection.
windowsupdate tries directly to connect to the internet and ignore the
proxysettings.
the firewall block the direct access from the client.
if i try with proxycfg -p "proxyservername", error 0x80244019 appears

the proxy is integrated in trendmicro viruswall smb, trendmicro support
cannot help.

help please, thanks