Looks much more like a kernel issue actually, the issue occurs randomly, no way to provide any reliable dmesg nor something else. Computer locks up and waits. Only thing to do is Ctrl+Alt+Del and pray that the next time it boots up correctly.
Some other users seem to report this issue on forums. ** Package changed: modemmanager (Ubuntu) => linux (Ubuntu) -- modemmanager hangs boot process https://bugs.launchpad.net/bugs/448994 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
