Why am I loosing alert messages?

I was just checking the HRP is in sick bay thread on the main board and found
that even though I was subscribed and respondeed to the thread,
I haven't gotten an alert since Friday, even though there are
many more I havent been alerted to.
I don't know if this is the only one or if there are others.
Also not sure if I am getting all alerts on conversations, and ad responses.
Also, my "all alerts" seems to be only a page now when it
seemed to be longer in the past. I'm sure you need to cut them off at certain lengths.
No hurry, just wonder and concern.
Thanks in advance.
Tony Martino