Repeated mousemotion event on notebook

SDL Development
1

I have a strange problem with my notebook.
Win2000 prof. - latest SDL (from devel. zip)

this is the sample code (compiled with VC6):

#include "sdl.h"
int main(int argc, char argv[])
{
if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_NOPARACHUTE) < 0) {
printf(“SDL_Init %s”, SDL_GetError());
}
SDL_Surface Surface = SDL_SetVideoMode(640, 480, 0, SDL_SWSURFACE);
if(Surface == NULL) {
printf(“SDL_SetVideoMode %s”, SDL_GetError());
}
SDL_Event event;
bool done = false;
while (!done) {

  while(SDL_PollEvent(&event)) {
     if(event.type == SDL_QUIT) {
        done = true;
     }
     if(event.type == SDL_KEYDOWN) {
        if(event.key.keysym.sym == SDLK_ESCAPE) {
           done = true;
        }
     }
     if(event.type == SDL_MOUSEMOTION) {
        printf("%i : %i %i\n", SDL_GetTicks(), event.button.x,

event.button.y);
}
}
}
SDL_Quit();
return 0;
}

If I run this program for a few second (without moving the mouse),
I find that my stdout.txt file contains something like this:
331 : 366 240
331 : 366 240
806 : 366 240
1306 : 366 240
1802 : 366 240
2302 : 366 240
2809 : 366 240
3308 : 366 240
3813 : 366 240
4312 : 366 240

it seems that every ~500ms something fires a mousemotion event,
but with the same x and y position.
I tryed with both directx and windib video driver.

This doesn’t happen on my desktop PC, so I think is something
notebook-related, maybe because the mouse is not a “real” mouse… ?

I know I can solve this problem testing the x and y with the previous,
but I’d like to know if it’s a problem of my notebook (IBM Thinkpad)
or if it’s something more…–
Skunk.