After installation, it will affect other programs' execution

If relevant, please answer to the following questions:
1. What version of Python(x,y) have you installed?
I use Python(x,y)-2.7.5.1.exe

2. Which components have you installed (Python(x,y) installer:
componentpage):
    a. Have you selected the "Recommended" component selection?
    b. Have you selected the "Full" component selection?
c. Have you selected manually plugins in the component list?
Whatplugins?
I have selected the "Full" component selsection.

3. Have you selected the option "Customize installation directories"?
a. Yes
b. No
Yes, select the "Customize installation directories"

4. If the answer to 3. is yes, what installation directories have you
chosen?
I just installed it into: "C:\pythonxy"

5. Where did you install Python(x,y) itself?
a. default path
b. custom path, which one?
I installed in: b. custom path.

6. Have you installed Python(x,y):
    a. For "Current user only"
    b. For "All users"
I installed for a. "Current user only"

7. What is your operating system?
a. Windows XP
b. Windows Vista
c. Windows 7
d. Windows 8
System is: c. Windows 7

8. Is the operating system 64 bit?
a. Yes
b. No
System is 64 bit, so: a. Yes. 

9. When you installed Python(x,y), were you logged in as :
a. a regular user
b. an administrator of the machine
Logged as a regular user.

10. If you are using Windows Vista/7, have you installed Python(x,y):
a. simply by double-clicking on the installer
    b. by right-clicking on the installer and selecting "Run as an
administrator"
Installed by b: by right-clicking on the installer and selecting "Run as an
administrator"

11. Regarding installed software on your machine, how did you clean your
machine before installing Python(x,y)  (multiple answers are possible):
a. you didn't do anything, you installed Python(x,y) directly on your
machine without precaution
b. you uninstalled any previous Python distribution (including the
official .msi)
c. you cleaned the Windows registry by removing all Python-related keys
d. you cleaned the environment variables by removing all deprecated
entries
Before install, I choose b option.

What steps will reproduce the problem?
1. Right-click the installer, and choose "Run as Administrator"
2. Choose "C:\pythonxy" as the installation path
3. Install the Pythonxy.

What is the expected output? What do you see instead?

Please provide any additional information below.

Pythonxy can install successfully, but after installation, when I open the cmd 
prompt and just type "ping", it will report following error:
===================================================
'ping' is not recognized as an internal or external command,
operable program or batch file.
===================================================
but if I type "ping.exe" in the cmd prompt, it will not raise up this error. 
And I uninstall the Pythonxy, then type "ping" in the cmd prompt, it was not 
raise the above error too, so I think this is a bug for Pythonxy installation.
Original issue reported on code.google.com by huz...@gmail.com on 11 Dec 2013 at 10:53
Merged into: #701
yuxiaorui / pythonxy

After installation, it will affect other programs' execution #705
