Rather than creating a new user, try simply moving (renaming) your "~/Library/Preferences" directory. Then log out and log in.
A new "~/Library/Preferences" directory will be automatically created, and you'll have lost all your preferences for all your applications, so beware... this could cause you other problems. However, you'll still have all your actual data. If it is a problem with preferences, this will fix it, if it does not fix it, you can rename/move the Preferences folder back again, and log out/in, and everything should be back to the way it was - nothing lost, nothing gained.
If this does solve the problem, you can then copy your preferences files back a few at a time, logging out/in after each few, to see which one(s) were causing the problems.
If this doesn't fix it, you can also try the same thing with the entire "~/Library" directory, but of course this has even more implications, and potentially more problems.