Ok, o problema foi o regkey, este funciona.
;------------------------------------------------------------------------
; Show hidden folders and files in Windows XP
;------------------------------------------------------------------------
; 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)
#h::
RegRead, ShowHidden_Status, HKEY_CURRENT_USER, Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced, Hidden
if ShowHidden_Status = 2
RegWrite, REG_DWORD, HKEY_CURRENT_USER, Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced, Hidden, 1
Else
RegWrite, REG_DWORD, HKEY_CURRENT_USER, Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced, Hidden, 2
WinGetClass, CabinetWClass
PostMessage, 0x111, 28931,,, A
Return