I installed Fedora 16 and then ran:

sudo yum install xen

Xen installed without errors and I rebooted. In the Grub2 list I selected Xen 4.1.2 and then selected the option: 

Fedora Linux, with Xen 4.1.2 and Linux 3.3.0-4.fc16.x86_64

The boot process starts (i notice that loading ramdisk is very short) and then shortly thereafter the boot fails and the system reboots without any error. 

I tried checking the boot log but I'm not sure I'm looking at the right log. 

The only problem I see in the boot is 

Started SYSV: sandbox, xguest and other apps that want to use pam_names$
Failed to start Xenstored - daemon managing xenstore file system