Comment 5 for bug 941094

Can you still reproduce this with a recent daily?

The segfault looks like a gtk issue or yet another case where something tries to access a widget we destroyed when switching step in the installer, as it's happening for you when entering the name of the PC, I'd suspect it to be related to the hostname resolving timeout in ubi-usersetup.
Some work happened in that area for beta2 (fixing a similar bug with preseeded installs), so it'd be useful to have this tested again.