Sharepoint error: ‘Edit document’ requires a Windows SharePoint Services-compatible application and Microsoft Internet Explorer 5.0 or greater

I had a user get this error when trying to edit a Sharepoint doc:



I read the necessary article from MS, and it was no help:

http://support.microsoft.com/kb/893698

but then I found this article:

http://yunetasblog.blogspot.com/2008/04/sharepoint-error-when-try-to-edit.html

which said that owssupp.dll add-on in IE could be disabled, which in fact was the case. So I enabled the owssupp.dll add-on in IE and then Sharepoint acted normally.