Folder Icons didn't change back to default after revert customization

Hi guys,
I've recently attempted to patch my folder icons manually with Resource Hacker. It didn't work, in fact it had worked for some folders but most folders remains the same beige icons.
I got frustrated since every step seems correct, but anyways I decided to revert back to normal, by replacing the custom imageres.dll file with the original to both System32 and SysWOW64 folder, and deleting iconcache.db for it to rebuilt.
Most icons revert back to normal after that, but except the folder icons in the C:\Windows folder, where some of them are still showing up with the custom icon.
I've restarted, tried changing the icon and rebuilt the cache file so many times, I even restored to a backup point before the change is made, but still no luck.
I've taken ownership for the necessary files and have run as admin when necessary.

Any ideas why this is happening? and if anyone can provide some tips to successfully change all folder icons, I will be really appreciated. Thanks.

forever alone =( but solved

exactly. I have rebuilt IconCache.db many many times and didn't solve the problem. Then I found out the thumbnail cache business in these horde of forum topics and fix the problem and enable me to go to bed in peace.

I'm actually surprise that most tutorials about custom folder icons out there only mention IconCache and didn't mention the thumbnail cache..isn't it suppose to be a crucial part?