Asus vh242h snow-y flickering?

So here's what is happening.

Once upon a time, this all worked out quite well. I bought the little adapter for my Macbook Pro (Official Apple one, if there's any other) and hooked my Asus monitor up through it via hdmi cable. It detects the monitor for what it is, which is awesome.

For some reason, when I try to use any resolution that is not 1080i or 720p, it will continue to act like it's displaying but is only a black screen, as if it's not even on/idled out.

When I switch to either 1080i/720p, however, it does what you see above. Here's what I've tried and they've all failed.

1. Switched HDMI cables.

2. Rebooted.

3. Calibration.

4. Mirroring.

5. Software Update (I'm up to date)

That's all I can recall doing thus far. I've been on Google on and off for two days, but no dice.

Any suggestions? This used to work just fine approximately six months ago.