Dashboard doesn't work

I have OSX 10.6.8 on a 2.66 GHz iMac with 6 GB of Ram. All has been working well until a few days ago when suddenly Dashboard stopped working.

It doesn't open from the hot corner selected or from the Applications in the finder. AFAIK, I have changed nothing anywhere. I'm not sure exactly when it stopped working as it is not something I use every day. It must have been several days before I noticed it. I do a complete clone of my hard drive every day. When I started the system from the external drive where I save the back-up, it didn't work from there, either.

Is there any simple way I can re-install or download Dashboard and get it going again? I would prefer not to completely re-install OSX if possible and have to reset all of my personal settings, if possible.

Thanks in advance for any ideas.