Very sorry--PMs are disabled on purpose. The PM spammers/phishers were getting out of hand and I need to upgrade the boards. Rather than shut down the whole forum system until I get an upgrade plan in order, I disabled PMs. I intended to post something here, but (clearly) forgot.
If it's any consolation, those PMs you can't read are probably from the spammers, and contain "virus alert" phishing links designed to try to visit their site and install malicious software on your computer.
Once PMs are back up please delete any such messages you see, and report the offending user to directly to me. Do not click links you get in a PM unless you have a very good reason to trust them.
Thanks, and I'm sorry I didn't post something about this when I shut down the PMs.