http://bugs.winehq.org/show_bug.cgi?id=5264
--- Comment #28 from Mike Cloaked mike.cloaked@gmail.com 2009-05-01 11:36:57 --- (In reply to comment #27)
I can confirm this bug is still present with wine 1.1.2 going to Insert>Object...>Microsoft Equation 3.0
This is what Word says:
This object was created in Equation. This application is not available to open this object. Make sure the application is properly installed and that it has not been deleted, moved, or renamed.
It is worth noting that the Crossover Office team will soon be releasing Crossover 8.0 and in this new version the Equation Editor works in Office 2003.
Presumably the knowledge about how this was resolved will feed back into Wine and will then become a fix for this bug.