Illustrator Cs 5 Problem: Shape moves on own, won't cover other shape

Question

I'm trying to cover a section of letters that have been outlines with a red box over a serif for a homework project. HOWEVER. Everytime I do this, it looks like I have it all lined up and when I make another point, the points move on its own to be off  and not cover the object Say I complete the box and try to cover the object by just dragging and dropping, it will avoid that area and move it off to one side or the other but never align with the actual object I'm trying to cover for a smooth and even coverage.  Trying to get the red box to cover the black serif and it won't do it.
How do I fix this?

Answer 1

When you open a new document using either the Web or Flash Catalyst New Document Profile, you will see, at the bottom of the New Document dialog box, that Align New Objects to Pixel Grid is checked. All objects created while this option is selected will be subject to this behavior.
If you wish to stop this behavior in an existing document, go to the Transform panel (Window > Transform) and open the flyout menu by clicking in the upper right corner of the panel. Align New Objects to Pixel Grid will have a check mark beside it.  Click on this item to deactivate it. This prevents the behavior in new objects, but has no affect on existing ones.
For already-existing objects, select the ones from which you wish to remove the behavior. If you do not see Align to Pixel Grid at the bottom of the Transform panel, click on the flyout menu, then click on Show Options. If all selected items have pixel alignment applied, the box at the bottom of the panel will have a checkmark in it. Click once to remove it. If some, but not all, of the objects have pixel alignment applied, there will be a dash in the box. Click on it twice, and the checkbox should be empty.