I figured it out for him through Teamviewer. It was apparently his headset drivers. If anyone else has this problem, try turning off your headset drivers, or just any unneeded program in general until client.exe stops crashing.
Not particularly a bug, but rather client.exe will crash if it detects any type of tampering going on. Don't know why headset drivers would be doing that.Cool i'll add it to the bug thread.
Check your messages. I'll Teamviewer with you.I have the a similar problem, but on Windows 10, and it doen't show any error.
client.exe show on Task manager, but it just stay there eating 25% CPU. I have another machine on Windows 10, which run it fine. Installed required files. you can Teamviewer if u like
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Edit: I tried to remove my headphone & microphone driver, still not loading