lion restarts all program after sleep

Hello,

I have come across the following problem:

I've set mac os x lion on my macbook unibody 2010. When I leave for 15-20 minutes, computer falls asleep and when entering my password all the programs are being closed and then restart again. During the sleep it loses internet connection. I've tried turning off the sleep mode, but in 15 minutes it still happens. It happens even if computer is working either from the battery, or from the electric socket. My friend with the exact macbook has the same problem. The problem with patch 10.7.2 remains.

Waiting for your reply,

Regards,

Sergej