I would have thought thet Microsoft would have the resources to go after someone using their name but it seems to have been around for several years.
They do take it seriously and do put time, effort and money into fighting the worst offenders.
However there are two issues :
(1) Its a cat and mouse game. It is not particularly difficult for new offenders to startup operations. If Microsoft chased after everyone it would be like a dog chasing its own tail, hence they have no choice but to prioritise. They've got a strong brand with a large install base and hence make an attractive target for all sorts of mischievous activities.
(2) Much of their effort relies on collaboration with various aspects of the legal system in order to trace the offenders. The problem is that certain jurisdictions (predominantly in the Far East) have a tendency to turn a bit of a blind eye to electronic offenses, or at least are not a particularly helpful collaboration partner.
there are now numerous complaints on Flyertalk about this
There are numerous complaints about most things on Flyertalk....
(e.g. there was a 10 page rant thread on there the other day about the First class BA lounge being "too busy")