I've been trying to fill out forms for school on adobe reader x.
The form has last name then first name, etc.
Well, when I type my last name into the box, it also puts it into the first name box.
And when I erase my last name from the first name box, it also erases it from the last name box.
I've tried everything I can think of and it's really beginning to get aggravating.
The problem is the form was not created properly. The behavior you're describing will happen when the fields have the same name. You can't correct it with Reader, but you can if you have Acrobat.
Makes sense. Now how do I fix it with Acrobat?
Assuming the document doesn't have security restrictions that would prevent it, you can use the Select Object tool (left-pointing black arrow) in Acrobat, double-click either of the fields, and rename it so it is unique in the form.