Cannot edit Object Equation

[Antonio Luiz]

I inserted an Object Equation in my document. When I try
to edit or open it, I receive a message like: this object
is corrupted or is unavailable.

I'm using Office XP with SP2. The Equation Editor 3.0 was
installed after SP2 has been applied.

Someone can help me ?
Thanks.

 

[Antonio Luiz]

Thanks!
The problem was fixed disabling the Norton Antivírus
Office plug-in.