I have the same problem. Shutdown or "init 0" works while restart or "init 6" not.
Restart operation is hanging with the icon of fedora.
Last events tracked in the /var/log/messages are:
kernel: [ 54.459661] DRHD: handling fault status reg 2
kernel: [ 54.459677] INTR-REMAP: Request device [[0b:00.2] fault index 1c
kernel: [ 54.459680] INTR-REMAP:[fault reason 38] Blocked an interrupt request due to source-id verification failure
after these events, I can see the next reboot, forced because I pressed the power
button, 1st time to turn off and 2nd time to power on.
I don't know if you have the same events.
I let you know if I find something of useful.
---------- Post added at 09:57 PM ---------- Previous post was at 09:39 PM ----------
I solved temporarily "my" problem by adding the parameter
inside the /etc/grub.conf (link to /boot/grub/grub.conf).
Now restart works properly for me.
This is the actual "kernel" line that I have:
kernel /vmlinuz-220.127.116.11-26.rc1.fc15.x86_64 ro root=/dev/mapper/VolGroup-lv_root rd_LVM_LV=VolGroup/lv_root rd_LVM_LV=VolGroup/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=it nointremap
pci=noacpi rhgb quiet
Hope that this solves your issue for now.