Icons blinking and registry security problems..

I tried to clear all contents of
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts
then set security permission to logger user name to be clear from:
create key
set value


But it responds very oftenly with icons flickering / blinking
so I undo the security setting.. but wile keeping on registry browsing under this key I came across:

1. The jpg filetype key and userchoice key were created
2. In userchoice key the logging user ACL was created, and
3. It's set to DENY on SET VALUE !

It's windows 10 behavior or an intruder's been screwing up ?
Please help me.. many thanks in advance