When troubleshooting problems with your Mac, it is a good idea to try to isolate it as much as possible. Even if you cannot pinpoint the problem, finding out where and when it crops up can help if you need to seek guidance from others.
One of the steps in doing this is to see if the problem you are experiencing is an account-based issue, or one that is perhaps more global in nature.
If a problem is more global, then this means it will affect the entire system, but otherwise it may stem from a specific configuration in the account you are currently using.
While the sheer number of configuration options for both your account and the system can make determining this seem like a daunting task, an easy way to determine whether or not a problem is global is to simply create a new user account, log into it, and try the task that was giving you trouble in your main account.
There are two options you can use when troubleshooting accounts in this way: the Guest account, and a new standard account
Select the guest account and check this box to enable logging into it from the login window (click for larger view).
The Guest account can be enabled on your system by going to the Users & Groups system preferences, clicking the lock to authenticate, and then selecting the “Guest User” option in the sidebar. In here, you can check the box to allow the Guest account to log into the system. This will create a limited account that can log in without a password; however, any files you save or settings changes you make will be removed when you log out of this account.
To prevent this when troubleshooting, you can create a new standard user account by clicking the plus button under the accounts list, and then filling out the fields to create a new account, followed by clicking the “Create User” button.
When finished with either of these tasks, you can get to the login window by logging out of your account using the Apple menu, or by choosing the new account or the login window from the Users menu that should be next to the Spotlight menu in your system menu bar.
When you log into the new or Guest account, configure the account and attempt the task that was giving you troubles, and if the problems continue then they are likely global in nature and cannot be solved by manipulating files or settings in your user accounts; however, if the problems are not continuing then they likely are stemming from a problem in your main account, and you can proceed with troubleshooting specific settings and configuration files in your account.
Note that when done troubleshooting, you can simply disable the Guest account or delete the new user account, to revert your system back to how it was.