I have the same problem. It happens sometimes every left mouse click, sometimes every few. Average about every other click. Screen tries to resize (in fullscreen mode) and the game hangs for a bit. Then it works again until next LMB click. Unplayable when you are constantly leaving the game to see your taskbar or desktop or a window resize.
i figured it out!
after banging my head against the desk for a week, i was about to ask for a refund, seriously, if you left click on what "would be" either of the 4 corners of the screen, the game ejects you to desktop. as you can imagine, you often have to drag the mouse diagonally to the "corners" to move the mouse around the screen, then when you click the game freezes and you get bonked to desktop, infuriating! i built a pc for my mom to try and get her into gaming, she's 61 years old, this is the first game she's ever played in her life, and i bought it for her birthday. i flew to toronto to "gift" it to her through steam and set it up for her, and then this happens! i flew back to calgary leaving her actually interested enough to play, but unable to.
i couldn't figure out what the problem is for the life of me, i scoured the ENTIRE INTERNET! no one has the slightest idea of what the heck was going on. I had also just installed windows 7 earlier that day that we tried From Dust, so it couldn't have been any conflicting software issues... all the drivers were up to date... WHAT COULD IT BE!!!!???
i set the display size to +150% in windows display options, so that the icons were bigger so that she could see, i lowered it to +%125 and now it works! you can see that the cursor is actually now prohibited from touching the absolute edge of the screen when you're on the main menu in from dust. FIXED!
if you have this problem, i really hope this helps, i was losing my marbles.
if unsure how to do what i said, right-click on desktop, click "personalize" then in the bottom left corner of that screen click "display" then don't set it to large (150%) set it to small or medium, and you're set~!