I get that error message. I am creating a data entry form that is tabbed. So, yes, I have a ton of controls on this form. Can I raise the max number of controls?
You can only add 754 controls to a form or report in it's lifetime regardless of whether they are still there now - i suspect you don't have this many on display so would suggest that the form design has mead you add/delete controls.
Consider moving every control on batch to a new form and see if that solves it.