LXDE - Menu icon disappears after a time

[pvasshep]

I'm using Linux Mint 12 LXDE on my Toshiba Netbook and have been having problems with the bottom
taskbar. i.e. the taskbar such as that at the bottom of this image:
http://www.linuxmint.com/pictures/scree ... e/lisa.png

After using the computer for sometimes just a couple oi hours, the 2 icons at the
bottom left (the one for the menu, the other to show the desktop)
disappear altogether. And the icons that start out on the right side - i.e.
the sound icon, the internet connection icon, etc. all move to the left.
And the icons for the various programs which are running either disappear or
get all scrunched up to the point of being unuseable.

How do I stop this from happening? Or if it happens, is there a way I can
fix it without shutting the whole computeer down and rebooting?
Is there maybe a way to put a shortcut to the menu on the desktop so i would still
have access to the menu?

Thanks.

--Kathy