Or try this
1. In a command prompt window, type echo %path%
This should display the PATH environment variable. In particular, it should have the directories C:\Windows\system32 and C:\Windows in it. If it doesn't, this is your problem.
To fix it, do this:
1. Right-click Computer and select Properties.
2. Click the Advanced system settings link on the left.
3. Click the Environment variables button.
4. Find Path in the System variables list box and click the Edit button.
5. Add those two directories, separated by a semicolon and terminated by a semicolon, at the front of the path environment variable.
6. OK out of everything.
Now, a bigger question is "What happened to the Path variable in the first place?"