[signal34]

I believe menu pop and clicks are found here:

[HKEY_LOCAL_MACHINE\Snd\Event]
".Scheme"="Curr0"
"EventMask"=dword:01F7ED
"EventCache"=dword:600
"Curr0"=multi_sz:"Alarm2","Empty","Alarm2","defaul t","Empty","Alarm2","infbeg","infend","infend","Me nuPop","HWandSW","Empty","Alarm2","infbeg","infend ","infend","alarm2","Empty","Empty","voicbeep","Re cEnd"

If you want to delete all sounds, just delete everything under the "Curr0"= key. If you want to just delete the menu pops and clicks, replace "MenuPop" with "Empty."