Now, I’m going to assume that you’ve already checked the Explorer settings, and so on. This fixes a condition where the thumbnails appear very briefly (they flicker on then off) before displaying the default icon. The standard settings don’t have any effect.
The trick is to delete the local icon cache. The steps are relatively easy – first make sure you have killed all instances of explorer.exe before beginning. Best way is to fire up Task Manager and end any explorer.exe process. Then run a command line (as administrator if UAC is enabled).
At the prompt type:
- cd /d %userprofile%\AppData\Local
- del IconCache.db /a
This will delete the local icon cache and reload an explorer instance. It works for me.