Hidden Files

I was havig some troubles with a WinXP machine at work.
I could not see hidden files, even after activating them in options.
So I had to go to the registry editor and do the following:
Find: HKLM-Software-Microsoft-Windows-CurrentVersion-Explorer-Advanced-Folder-Hidden-SHOWALL

then DELETE the value CheckedValue in the right window. (Its type should be REG_SZ and data should be 2.)
Finally create a new DWORD value called CheckedValue (same as above, except that the type is REG_DWORD). Modify the value data to 1 (0x00000001)..
Voilà.