I want to enable a pop-up menu when a text field has a particular value. The only way i could sort-of get this to work was by creating a calculation field which would have a simple if statement. The problem is i cannot change the value of the pop-up menu since it is a calculation field it is stuck on the default value of the pop-up menu.

Does anyone know another way to do this?

One way could be if a script would run when the condition was met in the calculation field (the cal field would be separate from the pop-up menu. can we run a script in a cal field?).

suggestions are welcome.

You can create a calculation field of Case( yourTest, serial ), and create a relationship from this field to the serial field. Then place a transparent, one row portal around your menu field. It will only display when yourTest is true.

Alternately, you can disallow access to the field and attach a script to it that first determines whether yourTest is true and Go to Field [yourField], if it is.