Sony VGN-TZ340NCP - Manual (Page 199)

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Troubleshooting
Why can't I use the Bluetooth devices when I switch a user?
If you switch a user without logging off your system, the Bluetooth devices will not work successfully. Be sure to log off before
switching a user. To log off your system, click Start, the arrow next to the Lock button, and Log Off.
Why can't I exchange business card data with a mobile phone?
The business card exchange function is not supported.