The support for RAM faster than 1066 is "unofficial", but it will run at whatever speed the motherboard tells it to run at. Just that Intel doesn't officially support more than that.

Are you still using a 32-bit OS? Have you tried swapping the two sticks around and using different memory slots? I'd say 90% of the "bad RAM" cases I've seen were solved by unsocketing and reseating the RAM stick a few times. But there are some bad ones that make it onto the market as well.