Right-click on My Computer; go to Properties; go to Advanced, then to Startup and Recovery. Select the default OS (if you can) and remove the option to display the list of OSs. If you are feeling keen, you can edit your boot.ini from here and remove the problem altogether.
Note: this just removes access to the second OS. I don't think you would actually have two versions installed, so it is probably just a problem with the boot.ini file.