If you've experienced this error before, like i have, (which ruined my server) you've got to read the problem in a literal sense. You do have another MySQL program running/installed on your computer somewhere and your goal is to completely remove it.
For myself I searched through all my files and folders up and down and finally gave up and deleted my old private server, until recently I decided to continue trying to fix it, so i downloaded an entirely new repack and tried running MySQL.
Of course It didnt work at all and had the same crappy error right? So this time I simply went to Add/Remove programs through my desktop and there I found a MySQL trial version that had somehow made its way onto my computer... so people who havent found this easy solution try simply adding and removing programs and look for any type of SQL program that is running on your computer
Note: You cannot find this through Task Manager (unless its actually up and running, in which case you'd see it on your task bar since MySQL programs dont run in a backround format)
Anyway, when you find this other MySQL program, remove it immediately and you will have your annoying (but easily solved) problem done with and you may now play your private server again
Sorry if this is obvious (I know it is) but some people posted and we're never properly answered with a solution to their problem