Preservign object with sessions (cont.)

Hi. I asked about it last Friday, but nobody answerd :-( I've learned a few new things: Object is correctly stored in session. Event int's type/class isn't changed when user vists a page, that doesn't need that specific class. But if I print serialized version of the stored object i got 'stdClass' (despite of my class stored in session). I've been using 4.0.0 (I was also trying 4.0.1pl2 but this versions seams to have some problems with user-defined session-handlers). How can I correct this? (if it's possible). Przem