I just got this problem reported to me by a lot of users. When they click the “Send a private message” button on the user profile page they are sent to the compose page with a different users name in the send to area, and it’s always random! It never works the way it is supposed to, I need this to be fixed ASAP I have a site with over 1400 members!

[@r-a-y Keymaster 13 years, 6 months ago]

Sounds like you’re using a caching plugin like W3 Total Cache.
If you have it enabled, disable it.

Right now, there are a few issues with using object caching plugins.

Stay tuned to the following ticket for updates:
https://buddypress.trac.wordpress.org/ticket/2636