I'm using xubuntu 12.10 on 2 laptops. I don't lock panel 1 (the bottom one). On the newer machine it's fine. On the older one sometimes the lower panel appears when I move the pointer to the screen bottom and then won't disappear. It's a bit annoying.
I can only think of one relevant difference between the 2 computers. The newer one has intel integrated graphics, which are pretty well supported in the linux kernel ... well, they damn well should be.
The older one uses amd graphics, which I know are not well supported in 12.10. For example smplayer will only display video if I use the x11 output module.
If I enter:
lspci | grep VGA
01:05.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI RS880M [Mobility Radeon HD 4200 Series]
And apparently amd isn't updating their drivers for that series anymore.
However, everything else I've tried does work on this machine even if I have to change the smplayer settings.
Actually it did it once yesterday on the newer one with intel integrated graphics too, when coming out of suspend.