The problem is that some program has been set to autorun when you run cmd.exe.
In my case it was ANSICON that was installed… and then I moved the file without properly uninstalling.
I found a solution in this blog post:
http://carol-nichols.com/2011/03/17/the-system-cannot-find-the-path-specified/
The short version is to find
HKCU\Software\Microsoft\Command Processor\AutoRun
and clear the value.