I managed to get my BB working over USB as IP modem, but when I try to connect via USB it gives an error message that the device drivers are missing. In the device manager I see under other devices: "bluetooth pheripherial device". I guess I have to get BB bluetooth driver for my windows 7 64 bit somewhere but I didn't find any. Reinstalling the BB Desktop manager didn't help.

Any suggestions what I can do are appreciated.

in desktop manager, look in the right corner, where it says options, click, go to connection options.
make sure its not set to bluetooth, and instead set to USB.

Also, it all depends on your bluetooth dongle.
Some work, most don't.
I always have "peripherial device" that windows just doesnt have a driver for.

I have tried all different kind of settings. With USB all works fine but with Bluetooth I get an error message now that the modem has a hardware failure.

I don't think this has anything to do with my bluetooth, it must be the blackberry software. Sync over bluetooth works fine, but the modem is just not working correctly. Definitely a BB software issue.