Acer Aspire One stalls if offline

I'm pretty sure this is not a problem with Xubuntu, but... I have an Acer Aspire One model number 522-C6DKK. I've replaced the original (*******) hard drive and installed xubuntu 12.04. And it works fine, online.

If not connected to the internet it stalls, usually half way through entering the logon password.

All the other problems seem to be unable to connect: mine is the other way round and I am foxed. Anyone any ideas? I'm beginning to wonder if the BIOS was tweaked in some way to ensure that ******* was the correct version, or something.