Periodically people may find that their user accounts have become corrupted, where system processes and applications will not function properly when running in that account. Depending on the severity of the corruption, troubleshooting and fixing the problems may sometimes be more effort than it's worth, with creating a fresh account being a quicker workaround, especially if upon testing a new one the odd behavior does not persist. In these instances, while sometimes a complete reinstallation of OS X is the most straightforward approach, migrating to a new account may be preferred if you need to ensure other user accounts and application installations do not get touched.
