Why is the indicator light on my dock under the Finder icon flashing ?

The light flashes and Finder wont open. Everything that was on my desktop no longer shows and I get a repeated "The application Spotlight quit unexpectedly" warning. I tried taking my battery out and resetting as well as restarting but nothing has worked so far. I tried ignoring, reporting and relaunching. Nothing stops it from coming up again. It appears every few seconds. It seems to be coinsiding with the flashing indicator light. All other applications are working except Firefox, Mail, and Skype. HELP!!!