This message has the following cause and solution:
You have not added source code control programs to your computer.
Click Yes to display this warning the next time you try to use source code control commands, or click No to disable this warning message.
For Visual SourceSafe users, run Netsetup.exe from your Visual SourceSafe folder to obtain source code control capabilites. For other source code control providers, rerun the Setup program for your provider.