SDL left mouse button event without press on startup - mouseevent

Question

On the start-up of my SDL program a left mouse button event is registered without me pressing the physical left mouse button. The next physical left button press is not registered. All other keys and buttons work normal. When clicking the .exe the mouse is not located within the location of the window.
Here are the specifications of that event (taken from the SDL_Event struct):
type=1025 (SDL_MOUSEBUTTONDOWN)
timestamp=24
windowID=1
which=0
button=1 (SDL_BUTTON_LEFT)
state=1
clicks=1
x=0
y=0
I am on windows 8.1 compiling with MinGW (gcc version 4.8.1).
I have SDL version 2.0.3
This is my source code:
#include <stdio.h>
#include <SDL.h>
int main(int argc, char* argv[])
{
SDL_Window* window = NULL;
SDL_Surface* screen = NULL;
SDL_Event ev;
SDL_Init(SDL_INIT_EVERYTHING);
window = SDL_CreateWindow("SDL", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, 0);
screen = SDL_GetWindowSurface(window);
while (1) {
while (SDL_PollEvent(&ev)) {
if (ev.type == SDL_QUIT)
return 0;
else {
if (ev.type == SDL_MOUSEBUTTONDOWN) {
if (ev.button.button == SDL_BUTTON_LEFT) {
printf("MOUSE DOWN\n");
printf("type=%d\n", ev.button.type);
printf("timestamp=%d\n", ev.button.timestamp);
printf("windowID=%d\n", ev.button.windowID);
printf("which=%d\n", ev.button.which);
printf("button=%d\n", ev.button.button);
printf("state=%d\n", ev.button.state);
printf("clicks=%d\n", ev.button.clicks);
printf("x=%d\n", ev.button.x);
printf("y=%d\n\n", ev.button.y);
}
}
}
}
SDL_UpdateWindowSurface(window);
SDL_Delay(5);
}
SDL_FreeSurface(screen);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
I have tried to solve it by calling SDL_PumpEvents() and SDL_FlushEvents() and while this removed the first (erroneous) event, the second press was still not registered.
Something strange I noticed was that it worked as expected when I opened the program .exe by right clicking and then pressing 'open'.
It'd be very grateful if somebody could shed light on this issue.