OK
I had this same issue of maximum connections exceeded in the past. I was using the normal connect not pconnect. I foun out that no where is my scripts was i using a mysql_close() statement. THe thing is with pconnect that it doesn't close the connection when the script ends, hence your message.
Not having used pconnect before i'm not 100% sure what you should do (short of using mysql_connect() / mysql_close() instead.
My guess is that there is a setting in the php.ini file specifying how long a pconnect is to last.
Found this in a post
pconnect only lasts as long as the server side process lasts. So the connection will be broken as soon as the resulting information from the server side process is sent to the browser.
http://www.phpbuilder.com/forum/read.php3?num=5&id=9031&thread=9013
Gary