Hello there! I don’t know if others are having this issue but since the Ashe patch, I have been having issues tabbing in and out of the game.
I used to alt-tab or Windows button to tab out the game to check discord notifications, something of a habit I have since kicked due to this bug. But since the patch, Overwatch now freezes completely and proceeds to kick me causing constant loss of Endorsement levels and in general making me feel like a bad person for leaving so many games abandoned. This also includes things like a pop up such as Norton or Windows alerts that can freeze the game.
This is getting very annoying as to get any access to my computer again I have to completely restart my PC as the Overwatch frozen window gets stuck overlaying everything.
Anyone have a fix?
i change my video setting to borderless window its works for me
Exactly thats happening to me, sometimes when I press alt+tab, the game just froze. I lost 200 points on ranked ty by this bug, and this stupid match design… You cannot rejoin because the match got cancelled when it doesnt even started yet but you still get penality and a lost… You also lose endorment points, I am back to 1 now. I will definetly change my settings to borderless if its works, but still I am really upset I got so many not deserved minus points, and nobody will give it back… Thanks Blizzard.
In about half the time when switching on other window and back on game, the game freeses. Screen becames black and i can’t switch even on task manager, only second virtual desktop helps.
It doesn’t happen only with me, my friend has that problem too (his situation’s even worse). This started since the optimisation patch. Reinstalling the game doesn’t help, reinstalling on other drive doesn’t help too.
Hi there friends,
We have seen this caused by a few things, the main fix is what Tceasars said. Switch the game to borderless windowed mode to resolve the problem.
In other cases, doing things like updating your video drivers and OS can resolve the problem. Turning off any overlays, even Discords overlay can help. Last, turning off any conflicting programs with a selective startup can help.
I hope to hear things clear up and if anyone has any other workarounds, please post them. 
/Nathardrick
Here I am replying so late, whoopsie. But playing borderless windowed does work sometimes. It no longer freezes but most of the time the taskbar remains at the bottom of the screen. This wouldn’t bug me much but it covers up the cool downs and if I try to do a sharp spin or look downward- such as a bomb jump with junkrat, it can drag the task bar around.
Pretty sure this is more of a personal problem though, just a computer that doesn’t wanna work with me.
I have the crashing consistently when the game is shrunk by alt-enter, so borderless is not the solution. And anyway, I play other, newer, games like AC:Od in fullscreen with no crashing on alt-tab. Windows install is new. Overlays disabled with great prejudice (even Windows game bar). No GPU overclock, RAM running at spec and tested. This is entirely y’all’s problem to solve. My guess is that when OW doesn’t regain all the resources it wants immediately, it handles this as gracelessly as possible and crashes.