|It seems that your explorer.exe is not associated with the shortcut for Windows Explore.|
I guess you open windows explorer in this way- click Start, point to All Programs, point to Accessories, and then click Windows Explorer.
Still if it does not open then you can use another 3rd party explorer software from here- http://zabkat.com/x2lite.htm
or else copy the explorer.exe file from another PC of your friend using the same OS..
Copy explorer.exe file from- C:\windows and paste it in the same path of your computer..
Just give it a try.. Or you have a third party explorer with you.. You can use it for the same purpose..