It's not me. I remember you've had trouble in the past with PMs but other times it works. I think I've only ever PMd you twice or three times in 17 years lol.
The only setting I have trouble with ever is My Mood up where we log in. I use "curves" in the Quick Style Chooser. Maybe it's the setting you have for viewing the page. There is always "Default" maybe that would work better? Anyway I don't want to confuse the issue.
As Jomar suggested, it could be something to do with a device other than your computer. Do you use your phone or some other device sometimes to post or check threads? Must be some setting on your computer if you're using that.
P.S. It says in the
FAQ - Private Messages that
you may need to delete some messages if you have too many. Worth a try. Maybe that's why sometimes it works and other times it doesn't.
Although I just found the place where it says how many PMs you can have and it says 1000 so unless you have 1000 then that's not the problem.
Just popped in to wish you all the best for Thursday.