ORIGIN ALREADY RUNNING

Here is a possible solution if you keep getting the error ORIGIN ALREADY RUNNING. This assumes you haven't let someone else "borrow" your Origin account or had it stolen.

Only one instance of Origin can run at a time. Please check other Windows accounts to see if Origin is running.

On my computer I run Firefox under a limited user account rather than under my administrator account. I do this to prevent a malicious website from being able to exploit Firefox and gain access to my computer. Since the Origin.exe program is running under an admin account, when Firefox tries to launch me into a game of Battlefield 4 it also tries to spawn an instance of Origin.exe and hence the error.

I can either run Firefox using my administrator account (never gonna happen), or I can use the Windows runas command to launch Origin under the same account as Firefox. If you are using the runas command you'll also want to use the /profile switch. I've decided to do the latter.