Lots of time I saw my notebook rebooting after closing lid or, in general, on pm-suspend event. Finally I found a solution, well documented on best-known Linux distros communities, to solve the trouble. In some old hardware and new kernel releases it's necessary to add a parameter on grub configuration file referred to kernel linux start entry. In grub.cfg search for 'vmlinuz-3.7.10-1.4-desktop' (in my case) and add at the end of row this parameter:
acpi_sleep=nonvs
To understand what's "nonvs" parameter it's possible to read sleep.c module infos in kernel sources (Linux/drivers/acpi/sleep.c). You can read:
* The ACPI specification wants us to save NVS memory regions during hibernation * and to restore them during the subsequent resume. Windows does that also for * suspend to RAM. However, it is known that this mechanism does not work on * all machines, so we allow the user to disable it with the help of the * 'acpi_sleep=nonvs' kernel command line option.