On a 64-bit machine with Office 2007 and either Visual Studio 2008 or Visual Web Developer 2008 Express, an upgrade to Office 2010 will cause Visual Studio 2008 or Visual Web Developer 2008 Express to hang when using the web editor or designer. The hang will reproduce by explicitly switching to design view on any web page (ASPX/ASCX/HTML/Master). It will also reproduce in a variety of actions inside the source editor of these pages, especially in cases where you have CSS in your page. Examples include pasting code, formatting, and using style-related functionality such as Apply Styles, Manage Styles, Build Style, or the CSS Properties. These symptoms will also occur after an explicit uninstall of Office 2007 on a 64-bit machine, which one would be required to do in order to upgrade to Office 2010 64-bit.
Note: This issue does not reproduce on a 32-bit OS.
The issue occurs due to incorrect removal of the 32-bit version of MSXML5 component by the 32-bit Office 2007 uninstall.
To resolve this issue, download the following update from Microsoft Download Center: