Without intending to reach a final decision on whether this behavior is desirable, I note that Firefox does the exact same thing with multiple windows open.
This report does not have enough information to even begin to understand what the problem is. In what way is the menu corrupt? A screen shot and an example of a failing desktop entry, if appropriate, would be helpful.
The next thing to check is the order in which lxpanel and compiz are started.
It is evident from the error you are seeing that the taskbar is using the fallback technique to raise the window. It should be using the _NET_ACTIVE_WINDOW request. The taskbar checks once at startup to see if the window manager supports this request, which compiz does. If it were the case that the taskbar...
