I'm using Fedora 15 and the latest LXDE. From time to time I see that
lxpanel freezes or maybe faults down such that I can't click anywhere except opened application icons.
lxpanelctl restart works well, but how can I fix this bug?
It could be anything from a driver bug, to bad RAM/harddrive. Check Xorg.0 log in /var/log/ (copy it to pastebin if you don't know what you're looking for). You can also try looking at dmesg or syslog but I doubt anything useful.
Make sure it's not your system, check the temperatures to make sure everything is running cool. Check your RAM with memtest to ensure it's all functional. Run atleast a quick test with smartmontools on your harddrive (takes 2 minutes).
Assuming it's not your system, you'll need to generate some debug info. Let's generate a couple backtraces! You might be able to get away with
Some of this is not so clear, so if you need clarification feel free to post back, but google has many good guides for creating backtraces with gdb.