For some reason once I add data from multiple tables to a form, the form either populates blank or populates w/ combo boxes that have 1,2,3,4... instead of the data from the field I need. This problem doesn't come up when I don't use data from other fields. Any idea what's happening?
Couple of things. I think we have discussed this before. Using a multi-table query as the Recordsource for a form is NOT recommended. This is what you are doing when you add fields from multiple tables to a form. As soon as you drag a field unto a form, Access creates a SQL statement that joins the multiple tables. The way to work with multiple tables on a single form is to use subforms. If the data is in a 1:many relationship, then you want to use a subform that displays multiple rows (either a datasheet or Continuous form). If the data is in a 1:1 relation, you can use a subform, but hide the borders, nav bar, etc. So that those controls appear as part of the main form.
As for the combo boxes. If comboboxes automatically appear when you drag a field to a form, it means that you have defined that field as a lookup field in the table. This is also NOT recommended and for the reason you are having an issue with it. Lookup fields in tables mask the data that is actually stored in the table. In your case, what's being stored is the Foreign Key value, not the descriptive Value. So, for example, if you have a Sponsors table, Each sponsor has an Autonumber PK. So if you select NIH, it might have a PK of 2. And what is stored is the 2, not the name, Lookups should be done on forms using list controls like comboboxes. Comboboxes have a Column widths property. So the RowSource of the combo would include the SponsorID and the Sponsor name. But you set the Column widths so the first column has a zero width. The user then sees only the sponsor name, but when they select the name the ID is stored. If you use the Combobox wizard to add a combo to a form, it, by default, hides that key column.