You're going to have to provide more details to find what's unique about your system/setup, what OS you're running, what patch version and optionally scripts you have installed, what your settings are, and where exactly you're encountering the issue... plus more detailed symptoms of what you're encountering, e.g. by "play" do you mean you're in a server, and if so do you hear the other players, is sound/music still playing normally, do your mouse inputs trigger jet/weapon sounds, does hitting escape trigger the lobby menu sounds, what happens when you alt-tab, what happens when you win-ctrl-shift-b, and so on.
Locking up to the point of requiring a restart is almost always related to a driver crash or memory issue. The game doesn't take exclusive control of anything under Windows, is relatively light on memory, and doesn't perform any complex operations on the GPU or compile shaders during gameplay. On an older system with a slow hard drive the game itself may freeze up momentarily when there's heavy fragmentation delaying a synchronous file load, but other than that? Certain custom scripts could cause the game to hang while processing an infinite loop, or it's possible a crash dialog could be hiding behind the game window (if you're running the preview patch, you should see a CRASHLOG.TXT in your GameData folder if this was the case). The computer wouldn't need restarting in those cases, though: you'd just have to close the game.
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You're going to have to provide more details to find what's unique about your system/setup, what OS you're running, what patch version and optionally scripts you have installed, what your settings are, and where exactly you're encountering the issue... plus more detailed symptoms of what you're encountering, e.g. by "play" do you mean you're in a server, and if so do you hear the other players, is sound/music still playing normally, do your mouse inputs trigger jet/weapon sounds, does hitting escape trigger the lobby menu sounds, what happens when you alt-tab, what happens when you win-ctrl-shift-b, and so on.
Locking up to the point of requiring a restart is almost always related to a driver crash or memory issue. The game doesn't take exclusive control of anything under Windows, is relatively light on memory, and doesn't perform any complex operations on the GPU or compile shaders during gameplay. On an older system with a slow hard drive the game itself may freeze up momentarily when there's heavy fragmentation delaying a synchronous file load, but other than that? Certain custom scripts could cause the game to hang while processing an infinite loop, or it's possible a crash dialog could be hiding behind the game window (if you're running the preview patch, you should see a
CRASHLOG.TXTin your GameData folder if this was the case). The computer wouldn't need restarting in those cases, though: you'd just have to close the game.