I'm currently running Arch Linux with:
lxde-common-0.4.2.-1
lxpanel-0.4.1-1
lxmenu-data-0.1.1-1
menu-cache-0.2.2-1 (newest is 0.2.5-1)
Every once in a while, with the current versions, I will have a completely blank menu and will have to restart LXPanel. It's annoying, but I have found no way to permanently fix it.
If I upgrade my menu-cache to the latest package in the arch repos, it gets worse. All I get are run and logout, nothing else. This has been happening for every single upgrade of menu-cache after 0.2.2-1.
Other than that, LXDE has been awesome.
Update:
This has been partially solved by using the script from the wiki:
http://wiki.lxde.org/en/LXPanel#Fix_emp ... in_LXPanel
I do hope that eventually whatever causes this to happen in the first place is fixed, but at least now it works even with the new menu-cache version.