The curse of the Q.
quite simply, rebind your lastinv key.
if you use the standard wasd imput config, rebind it to something else. capslock is a nice alternative. why? most people know this, not much of a discussion really, but rebinding it free's up your left hand ring finger to strafe left (helpful for obvious reasons.)
personally, i use mouse4.
ive played hl based games for a good 5 years now. wish someone had told me. only figured this out 2 weeks ago.