...but not here. Sorry about that. In detail this means that the page that you tried to go to
('/~/contact.aspx') could not
As a software developer, I really don't like to blame the user. I try to think that if anything goes wrong when someone is using my software, it's only because I failed to prevent it from happening. But in this case I can't. Based on the information that I have, I guess that you have either manually typed in the address into the address bar or, perhaps followed a favourite book mark. If you typed it in, there is nothing much I can do; please check your spelling and try again. If you followed a book mark, well then it might be my fault (perhaps I renamed a page which is a no-no when it comes to maintaining a web site). Either way, nothing much I can do about that right now. Again, sorry for the inconvenience.
By the way, "Arriving somewhere but not here" the title of a song by Porcupine Tree.