Emails (to your personal email address)? Or Alerts (that show on this board, in the upper right)? I believe you have to actually open the thread and read it, or you won't get new Alerts. And make sure you are logged in when you read the thread, otherwise it won't recognize that YOU read it. You might try using the "Mark Forums Read" button above to re-set that and see if it helps.
As for emails...make sure they aren't going to your spam folder. I know I've had emails end up there on occasion, even from people in my address book. Not sure why.
Those are my suggestions, hopefully something helps!