My friend and I both bought r4. Other works well but other freezes at loading screen. We have tried every trick like formatting with fat, fat 32, trying chinese firmware and papertrick. Always stuck at loading screen. Sometimes it says "SD/TF card error". Cards were bought from dealextreme and they came with kingston 1GB microsd cards. So, the problem is not in microsd card because both cars work with working r4. What you are suggesting we to do? Send it back to dealextreme and asking for freebies, or is there a way to get it working? And does someone got any experience about sending it back to dealextreme and do i have to pay shipping costs?