# A very strange problem with Overfull \hbox

The last two days I face a very strange Overfull \hbox problem.

I am writing a book and I am in the 4th chapter. I began writing a 5th chapter, but then I decided to include this in the previous chapter, i.e. chapter 4. And here is the problem. When I write instead of \chapter{Blah}, for 5th chapter, the command \section{Blah} (in order to include this in chapter 4), I take the warning Overfull \hbox (0.91098pt too wide) detected at line 26 ! The same thing happens also when I use chapter 5, with subsections. This is very strange. I searched the whole TSE but nothing could solve this problem.