Here Mark,

Give these a try...

The site Windows Guide Network under the Registry section contains all this kind of information.

Show Hidden Operating System Files

code:
User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
Value Name: ShowSuperHidden
Data Type: REG_DWORD (DWORD Value)
Value Data: ( 0 = Hide Files, 1 = Show Files)
Show Hidden Folders and Files

code:
User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
Value Name: Hidden
Data Type: REG_DWORD (DWORD Value)
Value Data: (1 = show hidden, 2 = do not show)
Show even the Hidden Extensions

NOTE: VERY DANGEROUS (Keep a backup of all values removed in case you need/want to restore)

code:
Find and delete occurances of the Value Name: NeverShowExt
System Key: [HKEY_CLASSES_ROOT]
Value Name: NeverShowExt
Data Type: REG_SZ (String Value)
Show the Administrative Tools Menu

code:
User Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced]
Value Name: StartMenuAdminTools
Data Type: REG_SZ (String Value)
Value Data: Yes or No