Your BIOS is running the RAM conservatively, so there's no real problem there. Until you iron out the instability, I wouldn't go messing with the timings.
To enable or disable Automatic Restart, it's pretty much the same on XP through 7, just right click on "My Computer" ("Computer" in 7) or press the Windows key (between CTRL & ALT) and the PAUSE/BREAK key. Then click the Advanced Tab (For 7, click "Advanced System Settings", then the Advanced tab) and look for "Startup and Recovery" at the bottom. Click the settings button there. UNCHECK "Automatically Restart" and then click OK, and then OK or Close.
Also, another thing you can do is download and run your system through a MemTest. Download and burn the ISO from http://www.memtest.org/
- you can also get a USB Flash Drive version from the site.
Run that on your system overnight and see if you get any errors, or if it can even run the test.
Two other possibilities are an overheating CPU (which you said isn't the case), or your power supply is of poor quality. I don't see your PSU mentioned here, so we need that information as well.