Lost session

[eluser]Blazer[/eluser]
I faced a problem with lost session too. Its happened after I reload my database from another server but now I don't understand why - table "partner_session" used for sessions saving doesn't changed so I think that is not a reason. Code is a kind of:

Code:

function __construct() {
  $this->project = $this->session->userdata('project');
  $this->service = $this->session->userdata('service');
}

function select() {
  $id = $this->uri->segment(3);
  if ($this->project = $this->Project->get_by_id($id)) {            
    $this->service = $this->Service->get_by_id($this->project->service_id);
    $this->session->set_userdata('service', $this->service);
    $this->session->set_userdata('project', $this->project);
  }
}

Userdata from session doesn't loading! Is this a really CI's bug?..

UPD: log

ERROR - 2008-05-28 23:37:07 --> Severity: Notice --> unserialize() function.unserialize: Error at offset 1062 of 1626 bytes Z:\home\partner.mobistic.l\system\libraries\Session.php 215
ERROR - 2008-05-28 23:37:07 --> The session cookie data did not contain a valid array. This could be a possible hacking attempt.