error message for Outlook express

[janesprando at comcast.net]

I was deleting some old messages in Outlook Express and kept getting a clock that didn't go away. So I used command/option /escape to quit Outlook.

Now when iIopen the program the program, I get this message: 
"An error occurred whil launching. The end of file was reached."

What does this mean? More importantly, how can i fix it so that i can get Outloo back up and running again?

Jane