I just tried acpi=off, now Ubuntu starts without problems, but I get the same error message on the following command "sudo wvdialconf /etc/wvdial.conf" that "no modem was detected..." Then I tried turning off sound in BIOS again (acpi is still off!), but on the command "sudo wvdialconf /etc/wvdial.conf" computer stopped responding. I waited for about 10 minutes, and restarted the comp. on the button... I did that again ("sudo wvdialconf /etc/wvdial.conf"), and comp. stopped responding again. Went to eat something :-), came back (after half an hour), and it was still there... Looks like there's no hope...