Symptom: default Windows 8 icons look wrong. For example "shield" icon for some .exe files and for unknown files (also for files without extension) etc.
Here's how to fix it:
0) backup your registry, just in case (I recommend also to create a restore point)
1) start regedit
2) navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer and expand it
3) find "Shell Icons" key (note: this key does not normally exist in fresh Windows 8 installation...
Here's how to fix it:
0) backup your registry, just in case (I recommend also to create a restore point)
1) start regedit
2) navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer and expand it
3) find "Shell Icons" key (note: this key does not normally exist in fresh Windows 8 installation...