Marc Lognoul's IT Infrastructure Blog

Cloudy with a Chance of On-Prem

Windows: Using a WebDAV Folder Maybe Very Slow on Windows Vista or Windows 7

On windows Seven and Windows Vista, you may experience very slow file browsing, opening and modification when against WebDAV folders (SharePoint’s Explorer View for example). This may come Internet Explorer’s (in)famous “Automatically detect settings” option


  1. Open Internet Explorer
  2. Go to the Menu “Tools” > “Internet Options” then go to the tab “Connections”
  3. Click on button “LAN Settings”
  4. Uncheck the box “Automatically detect settings”
  5. Close and restart all running Internet Explorer processes
  6. Restart the “Web Client” Service
  7. Start browsing again…

Additional Information

IE’s “Automatically detect settings” option is there to help the user in configuring a web proxy “automagically”. It actually makes use of the WPAD protocol to discover a web proxy by 2 means (listed by priority of application): 1)As part of the DHCP configuration received by the host or 2)by performing DNS request(s). Unfortunately, when none of them succeed, it may seriously slow down Internet Explorer’s opening but also, as consequence, make WebDAV browsing sluggish because the Web Client Service (responsible for WebDAV browsing) seem to perform auto-discovery more frequently.


SharePoint: A Bunch of issues with Windows Vista and SharePoint Explorer View

It’s critical to keep systems up-to-date with patches, the 4 issues described hereunder prove it again 😉 They affect Windows Vista only, not 7 or XP. Certainly because the WebClient went through a serious revamp with Vista, Seven drawing benefit from product maturation.


Explorer View does not work when connection goes through a forward proxy asking for authentication

When browsing a SharePoint site through a forward proxy (or simply web proxy) server requiring authentication, everything is working fine but when switching to Explorer viewing or simply trying to open an MS Office document, whether you directly get an “Access Denied” message or you get prompted multiple times for authentication (pop-up windows).

This problem occurs because early Vista’s implementation of the WebDAV redirector (aka WebClient) used by the Explorer do not handle correctly the HTTP Response 407 (Proxy Authentication Required)

Solution: install this hot fix ( or install Vista Service Pack 2. note: the hot fix requires SP1 to be present


Explorer View does not automatically forward credentials if the site does not belong to Local Intranet zone

A tricky one: let’s say that a user is browsing a SharePoint site that belongs to the Trusted Sites security zone of Internet Explorer while the browser is configured to automatically forward credentials for that zone (non-standard config). Although it will work fine with the browser, it will miserably fail with the Explorer View because on vista, WebClient does not rely on Internet Explorer security zones configuration and therefore does not automatically forward credentials under some circumstances.

Solution: Install this hot fix ( or install Vista Service Pack 2 and configure registry as described in the MS KB article related to the hot fix (this step is mandatory).


Explorer View does not automatically forward credentials if IE’s proxy setting check box “Automatically detect settings” is cleared

Pretty much derived from the previous issue, this one will behave identically.

Solution: install this hot fix ( or install Vista Service Pack 2


Explorer View might merge merge cookies leading to authentication issues (or other issues as well)

Cookies are often used to maintained state and sometimes to allow some kind of authentication mechanism, like form-based authentication.

In the case of authentication, products such as ISA/IAG/TMG may use so called “persistent” cookies to allow application to share authentication. This is typical when you want to seamlessly switch from a browser to an MS Office application when working with SharePoint.

Apparently, Vista’s implementation of the WebClient may accidently merge cookies when passing them to the web server or gateway, making them unusable.

Solution: install this Internet Explorer Cumulative Security Update (, which also includes functional updates solving that problem…

Credits go to Pascal B and Nicolas S both MSFT for this one. Thanks guys!