Hi,
If you can give us some more detail it will give us a much better chance at solving the issue. What environment are you using (is this a Workflow issue?), what language are you coding in, what is executing when this error occurs, etc.
Ed
Ed Hickey http://blogs.msdn.com/b/edhickey/archive/2010/04/21/how-to-post-effectively-in-forums.aspx