I'm trying to install a FC 16 PV guest.  After installation the guest doesn't load with: Error: Boot loader didn't return any data!
[2011-11-14 18:57:32 32321] ERROR (XendBootloader:214) Boot loader didn't return any data!
[2011-11-14 18:57:32 32321] ERROR (XendDomainInfo:483) VM start failed
Traceback (most recent call last):
  File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", line 469, in start
    XendTask.log_progress(31, 60, self._initDomain)
  File "/usr/lib/xen-4.0/lib/python/xen/xend/XendTask.py", line 209, in log_progress
    retval = func(*args, **kwds)
  File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", line 2820, in _initDomain
    self._configureBootloader()
  File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", line 3266, in _configureBootloader
    bootloader_args, kernel, ramdisk, args)
  File "/usr/lib/xen-4.0/lib/python/xen/xend/XendBootloader.py", line 215, in bootloader
    raise VmError, msg