Comment 1 for bug 148543

Got the same on kernel 2.6.19-4-server #2 SMP i686. Here's what I did:
shuerlimann@prolo1:~$ sudo xm create /etc/xen/sysadmin.cfg
Using config file "/etc/xen/sysadmin.cfg".
Started domain sysadmin
shuerlimann@prolo1:~$ sudo xm list
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 1893 2 r----- 39.1
sysadmin 2 128 1 r----- 4.1
shuerlimann@prolo1:~$ sudo /etc/init.d/xend
xend xendomains
shuerlimann@prolo1:~$ sudo /etc/init.d/xendomains restart
Shutting down Xen domains: sysadmin(save)...Error: Device 0 not connected
 SHUTDOWN_ALL .All domains terminated
/etc/init.d/xendomains: line 264: 5217 Terminated watchdog_xm shutdown 1
Restoring Xen domains: sysadminl prolo1 kernel: [ 1100.910599] ------------[ cut here ]------------
 prolo1 kernel: [ 1100.910983] kernel BUG at drivers/xen/core/evtchn.c:481!
 prolo1 kernel: [ 1100.911218] invalid opcode: 0000 [#1]
 prolo1 kernel: [ 1100.911426] SMP
 prolo1 kernel: [ 1100.912389] CPU: 1
 prolo1 kernel: [ 1100.912391] EIP: 0061:[<c0247cce>] Not tainted VLI
 prolo1 kernel: [ 1100.912394] EFLAGS: 00010046 (2.6.19-4-server #2)
 prolo1 kernel: [ 1100.913007] EIP is at retrigger_vector+0x3e/0x50
 prolo1 kernel: [ 1100.913223] eax: 00000000 ebx: 02080000 ecx: f5746000 edx: 00000017
 prolo1 kernel: [ 1100.913330] esi: c03dd900 edi: 0000010a ebp: 00000000 esp: ed7bfe60
 prolo1 kernel: [ 1100.913436] ds: 007b es: 007b ss: 0069
 prolo1 kernel: [ 1100.913524] Process xenwatch (pid: 13, ti=ed7be000 task=c14fb560 task.ti=ed7be000)
 prolo1 kernel: [ 1100.913632] Stack: c014b691 c03dd900 0000010a c03dd928 c014b355 c0131aee 00000000 00000001
 prolo1 kernel: [ 1100.913820] 00000001 e5890c00 00000000 ed7bfefc e5890c00 c0257ecb 00000000 c025834f
 prolo1 kernel: [ 1100.914203] e5890800 e5890c00 e6cb9ba0 00000002 00000000 00000000 ed7bfefc ed7bfec0
 prolo1 kernel: [ 1100.914601] Call Trace:
 prolo1 kernel: [ 1100.915824] [<c014b691>] check_irq_resend+0x61/0x70
 prolo1 kernel: [ 1100.916293] [<c014b355>] enable_irq+0xc5/0xd0
 prolo1 kernel: [ 1100.916751] [<c0257ecb>] __netif_up+0xb/0x20
 prolo1 kernel: [ 1100.917839] [<c025834f>] netif_map+0x26f/0x2e0
 prolo1 kernel: [ 1100.918907] [<c02573bd>] maybe_connect+0x1fd/0x520
 prolo1 kernel: [ 1100.919994] [<c024f2cf>] otherend_changed+0xaf/0xc0
 prolo1 kernel: [ 1100.921066] [<c024d28a>] xenwatch_handle_callback+0x1a/0x60
 prolo1 kernel: [ 1100.922160] [<c024e00d>] xenwatch_thread+0x11d/0x130
 prolo1 kernel: [ 1100.923242] [<c0135336>] kthread+0xf6/0x100
 prolo1 kernel: [ 1100.923637] [<c0105367>] kernel_thread_helper+0x7/0x10
 prolo1 kernel: [ 1100.923908] =======================
 prolo1 kernel: [ 1100.924142] Code: b8 01 00 00 00 c3 8d b4 26 00 00 00 00 0f b7 d0 0f a3 91 80 08 00 00 19 c0 85 c0 74 0e f0 0f ab 91 00 08 00 00 b8 01 00 00 00 c3 <0f> 0b e1 01 e9 8f 32 c0 eb e8 90 8d b4 26 00 00 00 00 0f b7 04
 prolo1 kernel: [ 1100.925282] EIP: [<c0247cce>] retrigger_vector+0x3e/0x50 SS:ESP 0069:ed7bfe60
 webmaster1Error: Restore failed
Usage: xm restore <CheckpointFile>

Restore a domain from a saved state.
!.
shuerlimann@prolo1:~$ l

The 'l' on the last line was the last reaction of this machine over SSH. It then just freezed, not pingable anymore.

Tell me if I can help by sending any logs or something...

Thanx
Simon