Is this a browser form?
If it is on the client, I think usually that error message has a button on it that says Details. But, basically, if you have filled out a form and the controls that are being marked as invalid don't show in the view you are using, you are probably not going to be able to submit that filled out form. If you designed the form, you should open the form in design view and use the Logic Inspector to help you find the controls with data validation (if this is InfoPath 2007). If you did not design the form, you should contact the person who did....
On the other hand, if you see controls that have a red asterisk in them or a red border around them, try changing the value or entering a value to see if that will get your data into a valid state.