Problems with a seperate thread for dinput

Basically I have 2D, tiled, turn based space game. I collect input
(keyboard and mouse) with a seperate thread that I currently have set to
collect 20 times per second.

The problem : Timing. Each of my screens (intro, character selection,
etc.) execute varying amounts of code (drawing, rule checking, etc.) so
keeping in mind the input collection at 20 seconds per second sometimes I'll
miss a mouse click and sometimes I'll have registered several mouse clicks.

For example on one of my screens I have a button that basically increments a
number each time it's clicked. Since there is not a whole lot of stuff
being drawn and/or other rule checking going on when I click the mouse
quickly the number will increment by 2 or 3 instead of the expected 1 per
click.

On a completely different screen that has more stuff going on if you will,
when I click the mouse on a button sometimes it doesn't register instead of
the expected 1 per click.

I know it's a timing issue and I can tweak it to work properly for a
particular screen, but obviously not for all the screens.

So I would like to have consistency along with appropriate input collection
frequency. How can I control this? My guess is by limiting the times
through the loop with something like gettickcount().

The flow of my program is basically like this. I'm leaving a lot out, but
enough to get the point across.

main()
{
loop(until user quit)
{
dispatch message
application->run();
}
}

application::run()
{
switch(what state am I in)
case : initialization
dointialization();
case : start_screen
dostart_screen();
case : char_selection
dochar_selection();
}

Using the example above the dostart_screen() subroutine has very little to
draw/do so clicks register quickly. Meanwhile, on the dochar_selection()
has a lot more stuff being drawn/checked so the clicks register slower.

My thoughts on how to fix this would be: (adjusting the top/main loop
only)

main()
{
loop(until user quit)
{
gettickcount
dispatch message
if(tickcount is >= 30 fps)
application->run();
}
}

Any thoughts?

Also I know I went overkill with spawning a seperate thread and doing action
mapping, but I was learning it at the time and thought I would use that
moving forward, especially if I was planning on ever doing a FPS/realtime
game. I think it would work out pretty well for a FPS/realtime game.

regards,
dn

I tried the gettickcount() idea and it worked.