Here is video how a guy fixes the problem: https://www.youtube.com/watch?v=1Zf_ADyj... All above answers were kinda helpful, but still had the problem from time to time. What I did, was similar to a solution from the video above, but I haven't removed motherboard, I've just inserted 1/4 of plastic card under the bottom slot (for like 0.5cm) and then inserted memory cards. So far so good.