Hello sir, I am newbie :-( .I have been testing all free server control panels for last two months .Like you i was also facing the XML error in the latest Ispconfig release .But Now it Seems to be solved .
I installed a fresh installation using the script
Now, It does not install the Php-Curl Installation ,Hence in shell prompt i ran
apt-get install php5-mysql php5-curl php5-gd php5-intl php-pear php5-imagick php5-imap php5-mcrypt php5-memcache php5-ming php5-ps php5-pspell php5-recode php5-snmp php5-sqlite php5-tidy php5-xmlrpc php5-xsl
And Now The package Updater Works fine
,No more XML Error .
I had tried to raise a bug in bugtracker but it was declined by project manager
saying there is no error in package updater.Yes there is no error in it .The error is with installation method .