"standby" under Lubuntu 12.04 with xfce-power-manager installed leads to irregular crashes (I guess crashes of the X-server). I could not find any useful information about the crashes but figured out that xfce-power-manager may be the culprit: After I deinstalled it and reinstalled xscreensaver instead, standby seems solid again. My system is a Thinkpad edge 13 (Intel).
That is a Lubuntu bug, not a LXDE bug.
If it's not clear in the Lubuntu home page that Lubuntu is NOT LXDE, then you might want to ask its developers to make it more clear.
LXDE = a collection of apps that make a modular and lightweight desktop environment.
Lubuntu = Ubuntu remix that comes with, among other things, with LXDE pre-installed.
Please bug report to XFCE developers.
The program xfce-power-manager is not written by us.
Thanks