Users getting Private Message notifications when there is no new Private Message

[techartist1]

I've been running 3.6.8 Path Level 2 for a year, and all of the sudden a new behavior has cropped up.

Here is a typical user comment:

I keep getting emails titled "New Private Message has arrived" from your site. When I come to the site, there's no new private messages. I've even turned off private messaging, and I'm still getting these emails every few days. Please make them stop!

Has anyone else seen this? I've done a search and it seems this problem is unique.

[Dismounted]

You may want to try disabling all your modifications temporarily.