I had a problem with my double glazing blog, where the Titles of the Posts list were only displaying 3 characters wide, so you had to read way down the page to work out the Title. More annoyingly, everything was fine with my Pages list.
The answer wasn't in changing the width of the column- my first guess. The problem was that there were TOO MANY columns enabled.
On ANY Admin page, try going to the top right of the screen, and look for the Screen Options button. Click that, and you are presented with all the options you can choose from to display information. I simply deselected a number of choices I didn't need. Hey, Presto, with less columns, my Title column became wider. Hope this helps.