The only thing you can miss from your old prefferences are the “Favorites” that will dissapear. So if you don’t have some special
“Favorites” to keep, just trash the old prefferences. If the problem continue after trashing the preffs, as Steven says, repair permissions, run maintenance, and DiskWarrior or Techtool. Anyway all thsi you should do it in a regular basis to make your system goes smooth.
rafael