Another disappearing session bug?

[eluser]SkiOne[/eluser]
I have a for doing a POST. In the method that receives it, it stores the vars in the post in an array and then stores that array in a session. I am using database backed sessions.

If I go back or forward (i.e. do a page load) the specific variable I am storing get's erased but others I have stored are there.

I checked the timezone set for the server, php and mysql and made sure they are all the same. I have seen the behavior consistently in firefox and most of the time in chrome; haven't even tried IE yet.

I am checking for and logging this variable as the first thing in my controller and I can see that the data is lost at that point but if I look in the db that variable is there before the page reloads.

I have done extensive googling and even tried the Native_session library and still no good.

Any suggestions?

Edit:

On closer inspection it appears to create a new session everytime. I checked the useragent field and set it to 255