Pkg xen devel - Aug 2010 - xen-linux-system-2.6.32-5-xen-amd64: Lenovo R61, kernel boots on baremetel, no boot with xen4 hypervisor

Today I updated xen-linux-system-2.6.32-5-xen-amd64 & dependancies (e,g.:
linux-image-2.6.32-5-xen-amd64):

apt-cache policy xen-linux-system-2.6.32-5-xen-amd64
xen-linux-system-2.6.32-5-xen-amd64:
  Installed: 2.6.32-20
  Candidate: 2.6.32-20
  Version table:
 *** 2.6.32-20 0
        500 http://mirror.csclub.uwaterloo.ca squeeze/main Packages
        100 /var/lib/dpkg/status

apt-cache policy linux-image-2.6.32-5-xen-amd64
linux-image-2.6.32-5-xen-amd64:
  Installed: 2.6.32-20
  Candidate: 2.6.32-20
  Version table:
 *** 2.6.32-20 0
        500 http://mirror.csclub.uwaterloo.ca squeeze/main Packages
        100 /var/lib/dpkg/status

The system still does not boot through the hypervisor, but does on baremetal.