I just started up the computer today and when I went to the menu, something was wrong- part of the menu is too narrow. This has happened before and I restarted and it went away, but this time that's not working.
Rightclick on the menubutton and start "Preferences".
Now the Gnome Configuration Editor will show up.
On the left side you will see "mintMenu".
Expand "plugins" and select "applications". Then on the right side scroll down and find "width". Change it's value to about 400.