Error 7

From GuildWiki

Error code 7 is an error message that is displayed by the game at times. It comes after the player has been disconnected from the game.

According to Gaile Gray it describes a connectivity error somewhere between the Guild Wars server and the player's end, which usually would mean some kind of hiccup at the player's internet service provider. While often an error 7 is the result of an issue on the clients end, ArenaNet is sometimes responsible, as is apparent when a large percentage of online players receive an error 7 at the same time.

In the Dec 20, 2006 update, a reconnect option has been added to the game, allowing the player to reconnect after an error. However, the reconnect option does not always work; also, the person can die and fail in the mission while reconnecting.