>I just had this same error and it was caused by my changing the ColumnCount in the Visual Class for my grid to 2 instead of its default of -1. Once I put back the -1, the form worked right. I wasn't able to make and save any changes to the form until the -1 was put back in for ColumnCount.

Thanks, this means my memory is not totally out of whack :). The rule seems to be that a composite object instantiated in any container object cannot have any of its members missing, i.e. cannot have fewer members than defined in its class.