2011/4/27 Jan <jan@agetty.de>
Could you please have a look at the permissions of the xend sockets under
/var/run/xend/*? Since virsh is being executed with the the privileges of
the currently logged on user, the driver might not be able to access the
respective socket for reading which causes the driver .

# ls -la
total 4.0K
drwx------  3 root root   54 Apr  3 07:09 .
drwxr-xr-x 19 root root 4.0K Apr 26 00:18 ..
drwx------  2 root root    6 Nov 24 15:56 boot
srwxr-xr-x  1 root root    0 Apr  3 07:09 xen-api.sock
srwxr-xr-x  1 root root    0 Apr  3 07:09 xmlrpc.sock

regards
Maciej