This was reported to me by I user:
i'm using the firefox browser and it gives me the option of having tabs open to different pages so i can open the forums, then hit 'new tab' and open a second instance of the forum on the second tab, i can log out of mookie and log into luket... the first tab still says mookie, as long as i don't touch anything; so it looks like I'm logged in as two different people at the same time. Now, if mookie's page had been open to a pm, and i typed in a reply and sent it, after logging in as luket... I'm not actually logged in as mookie, and as soon as the pm is sent it will tell me that I'm actually luket... in the right hand column, instead of saying 'read' or 'unread' , luket's pm says 'received' ... i just can't open or delete it
It looks to me like it's cookie confusion…
The problem is that you end up with PM's in your box the you cannot open or delete.