Question : drive mapping not working?

Greetings, what would cause the "Open in Windows Explorer" path to change as follows?

Change to:

http://servername/sites/site01/doclib

instead of

\\servername\sites\site01\doclib

This is the second client I've had this happen at.  The first client.it happened when everyone was issued new laptops.  

For this second customer, it's just happening all of a sudden.  Is it a network configuration, or internet explorer configuration that cause this (ie. changing from \\servername to http://servname for windows explorer view)?  If so what specifically might it be?

We have people griping now because they can't map a drive to their usual SP doc libraries.

Thanks in advance.

Answer : drive mapping not working?

The WebDav client is probably the issue. Various things update it (e.g. Office).

What OS and what version of Office?