In case you missed this update and you've seen that disabling the clientside WebClient resolved your issue with Sharepoint you might want to take a peek at this!
This download enables you to update the Web Folders component in Microsoft Windows operating systems, and provides additional functionality.
The article describes the Software Update for Web Folders that is dated March 15, 2007. This update fixes various issues that occur when you use Web folders from your client computer to connect to a server that supports Web Distributed Authoring and Versioning (WebDAV). Additionally, this update includes security enhancements to Web folders.
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