I found this thread after encountering the same issue - I'm using IE7
Beta 3 and I uninstalled Office 2003 Pro SP2, installed Office 2007
Beta 2, attempted to edit a Word doc in SharePoint Services v2 SP2
(which I administer in my organization) and Word (or Excel, etc) kept
crashing. I then backed out of Office 2007 Beta 2 and reinstalled
Office 2003 Pro SP2 and the problem persisted.
I did just try something and it seems to have worked. I'm back to
Office 2003 Pro SP2 at this point and IE7 Beta 3. I've done nothing
more than removed Office 2007 Beta 2 via Add/Remove programs.
When I connected to a Document Library in SharePoint and go to the Edit
in Datasheet view, then Edit in Microsoft Word, the document launched
fine. I haven't had a problem since in SharePoint's standard Document
Library view. It seems there just needed to be that first correct
connection and Office and SharePoint are back to communicting to each
other fine.
The other idea I had was to go to My Network Places, find the Document
Library and launch the file I needed. I never got to try that before I
found this work around.
I'm going to install a VM using Office 2007 Beta 2 and see if the
datasheet work around works. Otherwise, at least I'm able to use
SharePoint and Office 2003 without a problem.
John Ferraiuolo