Metroid Database.com

The fact that Other M has a minor glitch with the major consequence of forcing you to restart from the very beginning is not entirely news. But Nintendo has acknowledged it and they're doing something about it.

In a nutshell, prevention is the easiest solution. If you've not yet played Other M or if you plan to replay it, you should keep this spoiler-free bit of information in mind: once you acquire the Ice Beam, DON'T BACKTRACK! Keep going forward, fight the enemies and keep going till the next save point. Then you'll know for sure that you're safe. If you go backwards to the previous save room immediately after obtaining the Ice Beam, you run the risk of getting stuck!

If you find you're already stuck, fear not for there's yet a chance to salvage your save game. By simply mailing your save file (yes, mailing) on an SD card, Nintendo will return it back to you with the game playable again. Or alternatively, you can mail in the entire Wii though you'd have to be pretty desperate for this. (For the time it would take, you could just start again from the beginning.) Either way, shipping is at no cost to you. Why they don't have the option of simply emailing the save data is beyond me.

Another good practice would be to back up your save data periodically, either via the in-game menu or from within the Wii Menu.

I've always admired Nintendo for their ability to step up to the plate, admit when they're at fault and then take actions to fix it. It can be safe to assume that future prints of the game will have this bug fixed, though there's no telling how long that will take.

-Jesse D