Invalid Use Of Grid Units error is issued in the following situation:
The widget dimensions must be set using 'px', 'pt' or '%'. To use grid units you must set the 'Use Grid' to 'Yes' in the theme
The widget has its Width, Min. Height, Margin Left, or Margin Top properties set using 'col', but it needs to be set with 'px', 'pt', or '%' instead.
Change the property with the error to use 'px', 'pt', or '%', or change the 'Use Grid' property of the theme to 'Yes' to specify the property with 'col'.