This error was most frustrating when trying to help people remotely. After giving them the files through IM (MSN Messenger) however they are unable to run the install application I give them. This is apparently a built in protection from XP or IM.
The file has an attribute which prevents Windows from executing it.
Right click on the executable and choose "Properties" and look to the bottom of the "General" tab. Click the "Unblock" button provided. Now you should be able to run the application.