up and down panel disappear.
when the panel disappear，how can I check what happend
To get started, the first thing I would do is check that the panels are actually working properly once opened. This can be done with the following keyboard short-cut:
CTRL/ALT/t
This will bring up a terminal.
In the terminal, execute the following command:
mate-panel
Your panels should appear
I have this problem too when using marco. If you start another window manager using the terminal they return. Then you can start marco again. If it’s the same problem I have, you can still click items on the panel. I ended up adding a launcher for compiz on my panel in case I log in using Marco or switch to Marco at some point. You could try creating a script to delay the autostart of Marco. I’m pretty sure it’s fixed in 17.10+ (MATE 1.18).