If you try to insert a link to close to another item, the anchor tags get al mixed up with the Paragraph tags, and the links do not appear correctly.
Simple test, enter "test", then select and link. Then enter "test2" and link. You will notice that the HREF for "test" appears in the URL box, it has grabbed the anchor data from the first linked item.
Just look at the HTML for this post and you see what happens.
test
test2