I cannot recommend a system cleanup utility. Reinstalling W10 is a pretty effective way of cleaning up. Of course, I can't promise that will work. I don't know where you downloaded fceux from, how it may be hacked, what strange OS settings you use, what weird user name you picked, what odd add-on software you install. But the most likely explanation is a junked up system
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Your operating system is broken. Reboot, uninstall junkware, or use a system cleanup utility. You might also try deleting your fceux.cfg
Which system cleanup utility I must use? Should I reinstall W10?
I cannot recommend a system cleanup utility. Reinstalling W10 is a pretty effective way of cleaning up. Of course, I can't promise that will work. I don't know where you downloaded fceux from, how it may be hacked, what strange OS settings you use, what weird user name you picked, what odd add-on software you install. But the most likely explanation is a junked up system