If it's a particular user, put them on Ignore and then you won't get their PMs anymore. I did have to do that for one user as he would sent me a link to his thread everytime he posted asking me to reply. After telling him several times to not do that, I put him on Ignore.

I have had users get upset that I ask questions and then don't reply immediately when they respond back. But, I don't live here. I check the place in the morning and I try to check it again in the afternoon. If they can't be patient and wait, then that is their problem, not mine.

If its genuinely something that should be dealt with by PM, I wll reply, otherwise, if I have time I will tell people the same as Lynne (but only once), other than that, I simply dont reply.

I'd rather post a question in the open forum. That way my being stuck in stupid some times, helps others.
Pm-ing for help takes away from that. The more opinions you get on a problem the more likely you are to reach a solution. You just have to patient getting those opinions.
If you have no patients then warm up the VISA cause it's going to cost you.

It's one of those things that sometimes people aren't just reasoning logically, sometimes out of frustration and/or desperation. They forget the whole point of the board is to help. They sometimes forget that there's a search feature, and often don't check it for it's useful filters. They forget that entire board is going to see their thread, as opposed to the one PM they've sent to one person who may or may not be online anytime soon. They don't really think about the fact that if I was participating in a thread, that their PM is showing up right above my New Post subscription to the same thread. Desperation has made them think they're going to get lost in the shuffle, and slow reply or no reply makes them think they're being ignored. They often say "please help me", which is very polite and certainly a virtue, but it's kinda why we're here. And they really sometimes do think someone has the answer, not realizing that if no one has the answer, well, as I said, that wouldn't be very helpful if everyone one of us bumped the thread saying, "eh, I don't know. Good luck!"

I would double that or send them an invoice first :)