This is an odd issue, and I've found it nearly impossible to try and search for solutions because all you ever get is pages about how to use the snap feature, or disabling stuff that doesn't fix it. I've just come from Win 7 where it didn't happen. I use the win-arrow keys to keep two windows in half of my screen. The two problems I've had are that if I've gone to a full screen windows (such as watching youtube or other streaming video) when I come back from full screen, the window has gone from being snapped in half the screen, to just overlapping the other one. The other is that it would also overflow to my second screen (I have a widescreen, and then a 22" upright for various things), and be annoying. I've "solved" the second problem by moving my 2nd screen taskbar to the left side of the screen so it no longer overlaps, but I still get the snap issue. Is there a way to solve one or both of these issues?
Thanks. I ended up using a program called AquaSnap that managed to fix both issues, now I don't have any overlapping to my second screen when I'm supposed to be snapped to my main screen, enabling me to put the task bar back at the bottom, and now going fullscreen snaps right back into position after coming back from it. Who the hell knows why Windows couldn't get this crap right. Getting sick of how many programs I need to make Windows not s**t or just to have it function normally. Now I just have to find a way to fix the way Chrome occasionally decides no other program or window is allowed to show on top of it.