There must be no space between a semicolon and the next entry.

Set your path to

%SystemRoot%\system32\;%SystemRoot%\;%SystemRoot%\System32\Wbem\;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\OpenSSH\bin\;C:\Python27\;C:\Program Files (x86)\curl-7.23\;C:\Program Files (x86)\Git\bin\;C:\Program Files (x86)\nodejs\;C:\Program Files (x86)\PHP\;C:\Program Files\Mercurial

and it should work.

Only ; is used to separate directories in the path name. As a result, every character has to be treated literally.

This includes spaces. Otherwise, it wouldn't be possible to specify directories that end or even begin with a space (the drive letter is optional).

Set your path to

%SystemRoot%\system32\;%SystemRoot%\;%SystemRoot%\System32\Wbem\;%SystemRoot%\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\OpenSSH\bin\;C:\Python27\;C:\Program Files (x86)\curl-7.23\;C:\Program Files (x86)\Git\bin\;C:\Program Files (x86)\nodejs\;C:\Program Files (x86)\PHP\;C:\Program Files\Mercurial

and it should work.

I suppose the variable PATHEXT got modified. It holds the extensions of files that should be recognized as external commands. Yours probably doesn't hold the .EXE extension.

Executing set PATHEXT should display the following or something similar:

PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC

If it doesn't, change its value.

There must be no space between a semicolon and the next entry.

Set your path to

%SystemRoot%\system32\;%SystemRoot%\;%SystemRoot%\System32\Wbem\;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\OpenSSH\bin\;C:\Python27\;C:\Program Files (x86)\curl-7.23\;C:\Program Files (x86)\Git\bin\;C:\Program Files (x86)\nodejs\;C:\Program Files (x86)\PHP\;C:\Program Files\Mercurial

and it should work.