I'm using Archlinux 64bit, 32bit intel driver, nouvea driver and flash-plugin installed, according to Arch wiki https://wiki.archlinux.org/index.php/Steam
not any key can work.

use Chinese locale cause this problem, you can change to English locale solve it temporarily.

this is console output:

Running Steam on arch 64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1360966495_client)
Installing breakpad exception handler for appid(steam)/version(1360966495_client)
unlinked 0 orphaned pipes
Installing breakpad exception handler for appid(steam)/version(1360966495_client)
[0218/225511:WARNING:proxy_service.cc(646)] PAC support disabled because there is no system implementation
Installing breakpad exception handler for appid(steam)/version(1360966495_client)
Installing breakpad exception handler for appid(steam)/version(1360966495_client)
Installing breakpad exception handler for appid(steam)/version(1360966495_client)
PulseAudio connect failed (used only for Mic Volume Control) with error: Access denied
Generating new string page texture 7: 128x256, total string texture memory is 131.07 KB
Generating new string page texture 8: 32x256, total string texture memory is 163.84 KB
Generating new string page texture 9: 48x256, total string texture memory is 212.99 KB
Generating new string page texture 10: 256x256, total string texture memory is 475.14 KB
Generating new string page texture 11: 64x256, total string texture memory is 540.67 KB
Shutting down. . .
unlinked 2 orphaned pipes
CAsyncIOManager: 0 threads terminating. 0 reads, 0 writes, 0 deferrals.
CAsyncIOManager: 515 single object sleeps, 0 multi object sleeps
CAsyncIOManager: 0 single object alertable sleeps, 1 multi object alertable sleeps