Have you restarted your computer/Solidworks? that would be the first place to start. Then try the following
The registry file often gets corrupted and may need to be reset. Close Solidworks. Go to run and type in regedit (if you're windows 7 or vista open up the start menu and search regedit). Once you have regedit open, open up the hkey_current_user folder, open up the software folder and rename the SolidWorks folder to something like SolidWorksOld. Then open SolidWorks back up and try to recreate the issue.
If that doesn't work, you want to try to repair the installation from within the programs and features, and then try to recreate the issue.
If neither of those options work, uninstall and reinstall Solidworks.