Regd Hooks

My application will launch an instance of word.... In the launched word I would like to disable the system menu of the MDI window (only one window is opened).... (i.e) if the user clicks on the system menu of the MDI window he/she should not get the drop down menu....Iam having the hook procedures written in DLL and implemented the following hook procedures (WH_CALLWNDPROC,
WH_CBT,WH_GETMESSAGE,WH_JOURNALPLAYBACK,WH_JOURNALRECORD,WH_KEYBOARD, WH_MOUSE,WH_MSGFILTER,WH_SYSMSGFILTER,WH_DEBUG)... Whenever the user goes to the system menu (using left arrow or right arrow in the keyboard) the message WM_NEXTMENU is getting fired.... I trapped this message in almost all the hook procedures but Iam not able to disable the system menu....

Any help would be greatly appreciated....