New Intel iMac freezes at connection to internet via USB Modem

Well, here it goes again. The brand new iMac Intel that is freezes everytime I want to connect via external USB Modem from Apple (also brand new). I tried the fsck-fy command, the option-alt-p-r command and the shift-d command. Nothing helped. I exchanged the modem. Nothing there. The connetion via ethernet and DSL works fine however. So far the Apple agents were not helpful.


Well so far I have:
1. Ran the lang hardware check from the DVD. Result: everything fine.
2. Changed the modem.
3. Installed the system new (not restore).
4. Hooke-up a brand new modem (the third).
It still does not work. Everytime I want to connect to the internet over the external modem the Mac freezes up and I have to restart.
Tomorrow I'll send it back.