[Fedora-xen] Formatting pauses during install

I'm using Centos 5 dom0 on an x86_64 machine with 12GB of RAM. Tried to use virt-manager to install a Centos 4 domU (also tried with Centos 5 domU) but the tool limits the disk to 16000 MB. So switch to using virt-install and specified an 80GB disk. Everything proceed well until "Formatting / file system" which stops at 11% (~8GB of the 74GB / partition). Are there hard limits here that I'm missing? Thank you, Tarun Rally Software