As far as I understand your system is hanging and this causes automatic restarts. If so, I'd first recommend the following:
Restart the system into BIOS by pressing <F2> during the boot process. Once in the BIOS setup utility, press <F9> to restore BIOS default settings. Reset any customized BIOS settings. Clear all DMI event logs by setting the option to "Enable", which is located in the Advanced/Event Log Configuration section of the BIOS Setup utility. Press <F10> to save the new settings and reboot the system.
If the problem continues, please, provide more details regarding the problem description and details on how your system is set up.