Edit: Alpha, I need to know the following:
How many messages do you have in the different folders of your PM section (sent, inbox, etc) please? And especially have you reached the limit of your inbox?
Working on it ATM. It's something that shouldn't happen as it was fixed during the development of the modification, on JUly 11 2008, but I'm afraid this is maybe a side effect of the use of prosilver or subsilver2 styles by someone at some time that messed up the database to some degree, because the variable (or sort of) you mention is concerned by the modification used by both Athen Paladins styles.
Edit: no it doesn't
seem it's an issue with the database itself but I'd rather be careful, so still doing what is described in the next paragraph.
Deactivating subsilver2 and prosilver ATM just to be sure I eliminate a possible cause. I'll see if I can modify subsilver2 and then prosilver to make them fully compatible with the modifications. This will take two hours or more. Not saying it's necessarily that but I want to work in a clean environmenet.
Notes:
Is there anyone else having troubles with PMs?
Have you used subsilver or prosilver at any time, Alpha?