What exact message? What system? What's involved in your project? Have you done the usual troubleshooting liek enabling capslock when opening the file? We need a lot more info.
As Mylenium says, we need to know a lot more if we're going to help you. Please provide answers to the questions listed here: "FAQ: What information should I provide when asking a question on this forum?"
I had the same problem, enabled caps lock while opening the file and it worked!