TortoiseHg 3.3 "Failed to open path in terminal"

I'm using the 64-bit version of TortoiseHg 3.3 on Windows Vista64, and when I navigate to the Repository --> Terminal I get the following error:

I guess that I need to change a setting somewhere, and I do not know where to look.

I did navigate to C:\Windows\System32 and found that cmd.exe DOES exist in this directory so it seems to be that the /K title globalspiritualevents part is failing.

I also found that I can change the shell by opening Settings clicking TortoiseHg and changing the selection in the dropdown box for Shell on the right hand side.

I know that it is possible to navigate to the project root in a terminal window and start running hg commands, but TortoiseHg makes it more convenient.

What do I need to do to get the terminal to work from the TortoiseHg menu?

I can reproduce this. It seems to be a bug in 3.3. If you change the Shell in File, Settings, TortoiseHg and use the same command with forward slashes, or double backslashes, it works:

c:/windows/system32/cmd.exe /k title %(reponame)s

or

c:\\windows\\system32\\cmd.exe /k title %(reponame)s

It also works with the following since cmd.exe is in the path anyway:

cmd.exe /k title %(reponame)s