I am running Lubuntu 12.04 (see below) on a Dell Lattitdue E5520 laptop. I set it up for dual boot with the Windows 7 pro it came with months ago when I first got it and everything works fine except: it will hang if I tell it to reboot (right about the time it would do a final system shutdown and start the actual power restart.)
If I tell it to shutdown, it works fine and if I tell it to shutdown or reboot when booted into Windows it works fine (so it's not a hardware issue), but the reboot hangs in Lubuntu. I did some checking and haven't been able to find anyone else reporting this issue, so figured I would mention it and give any required logs, etc to help debug it (if that will help - it's not really a show stopper for me as I just shutdown, then power-up when I need to reboot.)


~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 12.04.1 LTS
Release: 12.04
Codename: precise

$ sudo lshw
[sudo] password for growlor:
description: Laptop
product: Latitude E5520 ()
vendor: Winbond Electronics
version: 01
serial: [REDACTED - Growlor]
width: 64 bits
capabilities: smbios-2.6 dmi-2.6 vsyscall32
configuration: boot=normal chassis=laptop uuid=44454C4C-5300-1044-8043-B1C04F365331
description: Motherboard
product: 0KCT5J
vendor: Winbond Electronics
physical id: 0
version: A01
serial: [REDACTED - Growlor]
description: BIOS
vendor: Winbond Electronics
physical id: 0
version: A05
date: 11/30/2011
size: 64KiB
capacity: 1984KiB
capabilities: pci upgrade shadowing cdboot bootselect edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi biosbootspecification
description: CPU
product: Intel(R) Core(TM) i7-2640M CPU @ 2.80GHz
vendor: Intel Corp.
physical id: 4
bus info: cpu@0
version: Intel(R) Core(TM) i7-2640M CPU @ 2.80GH
serial: To Be Filled By O.E.M.
slot: CPU 1
size: 800MHz
capacity: 4GHz
width: 64 bits
clock: 100MHz
capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid cpufreq
configuration: cores=2 enabledcores=2 threads=4
description: L1 cache
physical id: 5
slot: L1-Cache
size: 32KiB
capacity: 32KiB
capabilities: internal write-back unified
description: L2 cache
physical id: 6
slot: L2-Cache
size: 256KiB
capacity: 256KiB
capabilities: internal varies unified
description: L3 cache
physical id: 7
slot: L3-Cache
size: 4MiB
capacity: 4MiB
capabilities: internal varies unified
description: System Memory
physical id: 28
slot: System board or motherboard
size: 8GiB