session dropping data

'lo, anybody ever experience this: 1. i start a session w/ session_start() 2. register some vars w/ session_register() 3. click to next page, everything cool. all vars are there, and session id is same 4. any other page, all session vars gone, but sessid is still the same. so session is persisting, but data is being emptied from it. any help would be excellent. thanks, dietrich