Formulas contain white squares until double click on them

[Trith]

Hi,
My formulas were ok when I save the document. But now when I open it, all the greek letters are displayed as white squares. However, everything becomes correct when i double click on the formula. The squares are also there when I print the document. Is there any solution to that problem other than double clicking on all my formulas every time I open the document ?
I use openoffice 3.2.0

thanks

[Trith]

Actually I realize that this document was created using Libreoffice and not openoffice. If I click on the formula so that the format becomes good again, and then save, and close and reopen, the format is still correct.