Hi,
I can fix this using graphics - although that causes another little problem in my current design - but I want to use text.

If I make the first letter of a text link a different point size from the rest, then the whole word fails to light up during a mouse over. If you're moused over the big letter, that lights up, and ditto for the smaller size letters. So a mouse over looks like this:

"un-moused over" = Home

"moused over" = Home or Home depending on where the mouse pointer is.