How to reliably unstuck ctrl alt and shift ( not just by send() )

due to the nature of what I am doing, my keys will get stuck, unavoidable, I just need a reliable _clearKeys()

My observation so far:
send(key up) works ALL the time for normal keys, ie. asdf's

same can't be said for ctrl alt and shift
in a simple ctrl click:

send("{ctrldown}")
for $ i = 0 to 4
mouseclick("left", 11, 11)
next
send("{ctrlup}")

in my particular instance, send("{lctrl down}"),  send("{lctrldown}"),  send("{ctrl up}"), send("{lctrl up}"), send("{lctrlup}") do not work or they will not free the ctrl key at the end.
only send("{ctrlup}") works, but not always either.
in severe cases, even a send ("ctrl") will get the ctrl key stuck (SendKeyDownDelay=30 or higher)

What I am afraid is that, once the ctrl key is stuck in down position, all the subsequent send(key) will be interpreted as send(ctrl+key), EVEN the send( ctrl up) attempts.
I would like a function that is lower level, something  like _isPressed("12"), that can just clear all the "down" keys.


my system is x64 windows 7.