Just to add, I was getting this exact error (along with a few other memory-related errors) when one of my RAM sticks was failing. I replaced both sticks of RAM and the problem went away. If you get this error a lot (or BSOD in general) after a while it will screw up your Windows install. I would suggest a reinstall and trying some different memory (maybe just 1 stick of 512 at a time) in different mobo slots to see if you can recreate the problem.
You should also try running memtest86 on your system to test the stability of the RAM under load, it may help you find a stick that isn't functioning up to par.
You should also try running memtest86 on your system to test the stability of the RAM under load, it may help you find a stick that isn't functioning up to par.