Hi Jeff,
I ran into similar problems when trying to squeeze stairs in some tight open space between walls. I have three suggestions that worked for me:
1) Zoom into the scene as far as possible this allows you to move the object more precise, or
2) Make the initial size of the stairs smaller and change the dimensions when you have inserted the stairs on the right location, or
3) Remove some walls before trying to insert the stairs and redraw them when you've inserted the stairs successfully.
Sebastian