Go to Options > Audio Setup > Audio Device and set the device to Windows Audio. Also, click the Control Panel button on that screen and uncheck the Exclusive Mode option there. You’ll know it the device is “online” and ok to use if it’s text is not italic there.
Similarly, go to Windows Control Panel > Sound > Playback, select the playback device and click Properties > Advanced and uncheck Allow applications to take exclusive control of this device. Also be sure that the sample rate in Studio One (Song Setup > Sample Rate) is the same as the audio device sample rate in Windows Control Panel.
If that doesn't work try using ASIO4ALL as the driver instead of Windows Audio. http://asio4all.com We don't support that driver for purposes of setup or troubleshooting but it may solve your issue.