I am running Windows 7 x64 and used the task manager to capture a dump by using the “Create Dump File” context menu command on my Firefox 11 beta process that had frozen when I exited (window disappeared, but process remained – with 75% CPU usage). Visual C++ Express 2010 complained that “You cannot debug a 64-bit dump of a 32-bit process, you must collect a 32-bit dump of a 32-bit process.” That’s when I found this post  which mentioned that the 32-bit task manager is actually available at C:\Windows\SysWOW64\taskmgr.exe and should be used instead.