It looks like some old text is getting left around, and is somehow superimposed
on the current output.  In one case, the old text was visibly a display that the
connection had been lost, then when the connection came back, the text didn't go
away.  But it seems to happen other times too.  Perhaps the text is being drawn
with XOR, so if anyone neglects to remove the old stuff it hangs around.

I assume what this is a firmware issue, though I am a bit vague on the
responsiblity for display management.  It does clear up if I do a real power
cycle on the squeezebox.