It seems that iPhone and Windows 7 have problems with tethering over Bluetooth on Lenovo notebook.
When you try to connect your iPhone with notebook using Bluetooth you will receive driver error for “Bluetooth peripheral device”. Of course you can control everything on your iPhone but you couldn’t connect to internet using tethering.
I don’t know why is this happened but solution is simple.
You must go to Control Panel – Devices and Printers. Right click on your iPhone then Properties – Services
Uncheck option Wireless iAP
Click OK
Now right click on your iPhone again
Then Connect Using – Access Point
And now you are connected to internet using Bluetooth on your iPhone
Dubravko Marak Blog 