Help with new S9 - Freezing, Random files, Reset button issues

[jomsie]

I didn't properly eject it one time from my iMac, now there are random files in my movie folder "system/flash_UI/????.sfw"

I have trouble now resetting the device when it freezes. Sometimes it's back to normal, but I don't know how to get rid of those random files because they don't appear on my iMac. Keep in mind I do have a PC. Any suggestions? Help me out please.

EDIT> I tried reformatting the device on XP, I didn't want to do it at first because I was scared I might lose the UI entirely. It's back to normal for the time being .