The following trick will fix it:
- Double-click the table to edit it.
- Select all the text inside the table.
- Click the paint bucket icon in the top toolbar to choose a different fill color (e.g.: black) and click OK.
- Now preview the site, and the text should be black.
Note that it's not enough to just click the table and change the color - you do have to actually select the text inside the table before changing the color.