Okay I read the sticky and the Guild Wiki article about Err=58 I kept getting it a while back so I deleted my .dat file and re downloaded it using -image. It worked so I played and whenever I left my pc I'd leave my computer on to keep downloading with -image.
Today I just finished downloading and when I got back to Guild Wars whenever I'd log in I'd either get a long "Connecting..." message or:
"Guild Wars was unable to connect to any login servers. This is very likely caused by an Internet routing issue."
So is it my .dat file causing this? Do I have to re download again?
Probably not. I've been getting that error intermittenly this evening, and my dat file is fine. There've been problems with lag and connections all night, several others were saying so ingame as well.