One of my test Centos 5 containers was on a partition that filled up and it threw all sorts of errors and stopped responding but now I can't boot it again anymore.

All the console shows is the Linux Penguin on the top left corner and the xm console says "usbcore: registered new driver hub" and has halted there.

Centos 5 Xen container stuck/frozen won't boot on "usbcore: registered new driver hub"

Another great way of troubleshooting is booting from the console, you at least see the GRUB options and manipulate them if need be:

xm create -c nameofyourXenVPS

 When booting this way it is now stuck on PCI: setting up Xen PCI frontend stub

 After removing the video display/console from Virt-Manager here's what I get now:

xen_mem: Initialising balloon driver.

If you enable APIC it freezes at:

Brought up 1 CPUs

APIC is disabled but now I'm stuck again on this:

It's still stuck on PCI: setting up Xen PCI frontend stub

 After updating the xen packages:

It gets stuck on:

Linux Plug and Play Support v0.97 (c) Adam Belay

Now it's stuck here:

checking if image is initramfs... it is

The problem seems random.

Now randomly I'm getting this far (it's as far as I've ever got):

xen_mem: Initialising balloon driver.

Now I get this far:

NET: Registered protocol family 16