We really need to know what type of Form we're dealing with, here! The use of the term 'columns' makes it sound suspiciously like you're talking about a Datasheet View Form, in which your only real option is using Conditional Formatting off of the Ribbon. As June7 suggested, you can only use VBA code for this kind of formatting on a Single View Form.
I've never heard of limitations on the number of Controls that were being used with CF, but how many Fields are we actually talking about, here?
Linq ;0)>
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007