Dynamic text shifts when style changes

I have some dynamic text fields that are set up so that when you rollover them (actually a button behind them), their formatting changes. This is done with some basic actionscripting, setting up 2 different text format variables and attaching one or the other to the text field when a button is rolled over. The only thing that changes is color. When the text first appears all is well. But when you rollover the text and the color changes, on certain browsers an extra space can get inserted at the beginning of a new line, sort of like the old bug where text wrapping messes up and moves a space down to the beginning of a line. This happens on IE 6 and 7 and Safari, not Firefox. The player is 9. THanks.