If the system's locking up even while in BIOS, I'd recommend the following just in case there's a BIOS corruption:
Reminder: Please, ensure you wear an anti-ESD bracelet on an anti-ESD surface (see http://tinyurl.com/7oobzc).
Unplug the power cord, remove all non-basic components; remove the RTC (Real Time Clock) battery and leave it out for 20 minutes. After this period of time, insert the battery back in, connect the power cord back in, and turn the system back into BIOS; then, do the following:
1. Once in the BIOS setup utility, press <F9> to restore BIOS default settings.
2. Reset any customized BIOS settings.
3. 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.
4. Finally, press <F10> to save the new settings and reboot the system.
Note: A basic computer configuration would consist of the following: keyboard, mouse, processor, memory, hard drive, CD-ROM, floppy drive, video card, and monitor. No other add-in should be installed.
Hope that helps!