There are no generalised issues with the PM system, it may be an issue either with your account, or your method of sending them.
Recently, I sent PM's to couple people and either my PM's aren't reaching them, or they're just not replying (includes Joe and Waterworth and others). I've sent multiple times to the people and they have not replied. Are there problems with the forums?
Upon checking the system, it would appear you have never sent a PM. Please attempt to send me a new one, and also please attempt to reply to the one I have sent you.
Once you have done both, please reply here so I know you have done.