Hmmm. The segmentation error, may be the culprit. Sometimes this error happens when it tries to read or write to the memory that it shouldn't. (Though not sure as to why you got this error) And not knowing what steps you took after the fact, maybe you inadvertently made a mistake with something.

You should be able to edit your sources.list file, especially if you are running as root. If you can't, I humbly recommend, just scrap it, and start over since you just started a fresh install. See if you can avoid the first trouble of the mirrors, try using a wired connection to start the install.