UPDATE:

After review I've found that my connection to the session cookie is 
staying open on everypage, but the information in the cookie seems to be 
randomly dropping out.  I'm echoing my SID on everypage, so I know the 
connection is there, but randomly on some pages... the session variables 
completely dissapear.  Then sometimes I can hit refresh and they'll have 
value again, but other times that doesn't happen.  Anyone have any guesses?