To ensure minidumps are enabled: Go to Start, in the Search Box type: sysdm.cpl, press Enter. Under the Advanced tab, click on the Startup and Recovery Settings... button. Ensure that Automatically restart is unchecked. Under the Write Debugging Information header select Small memory dump (256 kB) in the dropdown box (the 256kb varies). Ensure that the Small Dump Directory is listed as %systemroot%\Minidump. Click OK on each window to get out. Reboot if changes have been made.
Power off or restart is usually caused by a crash/BSoD.
Change the settings listed above and let it sit for a while if it crashes again, it will be making the dump files.
After the next crash follow these instructions: Blue Screen of Death (BSOD) Posting Instructions