Icons vanish from tray or stop working- Lighthouse64 mariner

[titus]

Hello,
This is a new one for me. My installation of Lighthouse64 works perfectly except when I'm doing a long printing job (as I am now). The tray loses all the icons on the left hand side (menu, browser chooser, desktop switcher etc.) and the clock and shutdown button from the right. I'm left with Glipper, Interface, Volume and Sven in the usual place (just to the left of where the clock should be). The remaining icons work normally and I can switch desktops by right clicking and selecting the required destination. When I shut down and re-boot, all is back to normal.
My PC is fairly high spec, for me, 4 core AMD and 8G of DDR3 and the processor temp is at 37 degrees so I don't think the printing should be overworking it.
Anyone experienced anything similar?
P.S. This is now a totally Puppy household, Lighthouse on the main PC, Precise on the back up and Lucid on my wife's laptop.

EDIT: Today the icons have not vanished but they don't work. The digital clock freezes (The analogue, widgets clock on the desktop is fine) and although I can switch desktops by the scroll wheel and the right click method nothing in the tray works except the four icons mentioned above.