I know how to fix the problem (At least until the Techs can figure out the cause)

.
However many
New Messages you have in the negative, for example I had
-8 New Messages, Send yourself a PM
by clicking on your username, (I just wrote
Subject: Hello and the
Message: Hello again) then answer it.
After you have answered your own PM, delete the original one, and your Negative count will go down.
Repeat for each Negative New Message.
It worked for me.
