Hi Jules,
I have downloaded your file on a Mac machine (it seems this MobileMe thing doesn't want to work on any OS but Mac OS X) and it can be registered without problems with StarAlignment. Since you have uploaded only one file, I have duplicated it, rotated with the Rotation tool and resampled it to 40% of its original size with Resample. Then I have used StarAlignment to register it to the original without any issue.
If you increase the maximum distortion parameter to 0.68, StarAlignment cannot register this image because it has tracking errors and all stars are elongated, hence SA doesn't find any star. This is normal behavior. However with the default maximum distortion value of 0.5 it works perfectly.