iMac Randomly Shuts Down, Help?

[C0NFUZ3D]

We just got the Aluminum iMac for a replacement, and it's been randomly shutting down for me, and me only
Usually when I am typing though, It's kind of annoying
Any help?

 

[WildCowboy]

Could be bad RAM, but it sounds like it's definitely under warranty, so Apple should take a look at it and be able to figure it out.