This is probably due to tab order settings.
If you go in layout mode and then go to the Layout menu and choose "Set Tab Order" you can determine which field is entered first and what field you tab to after the first field.
You'll see all your fields on your layout with a number next to it.
That's the tab order; And you can go ahead and change numbers etc.
If you don't want to go to a certain field you can just remove the number next to it.
Play around with that a little. I'm sure it will help.
Thanks! That solved the problem!
You might also consider setting the drop down fields to display the arrow. WIth the arrow field selected, tabbing into the field does not deploy the drop down, you have to click on the arrow to drop down the value list.