Internet Explorer 9 and SharePoint 2010: Your client does not support opening this list with Windows Explorer
When you want to open a Microsoft SharePoint 2010 library in Microsoft Windows Explorer you can get the error:
Your client does not support opening this list with Windows Explorer.
This was due to installing a very old version of the SourceGear Client v3.1.9.
I solved this issue by using the same trick as with the IE 8 tab hang issue http://www.roelvanlisdonk.nl/?p=871