Error: not well-formed

Error: not well-formed, the following query string is not wellformed, browser causing error not well-formed

function GetChatLink(user)
{
var url= "Server.aspx?action=Login&u" +user;

return url;

}

Response.Redirect("OtherPage.aspx") causing problems

Response.Redirect("OtherPage.aspx") was causing a problem "System.threading.threadabortexception" then I use it with setting flag to false

Resoponse.Redirect("OtherPage.aspx",false) now its working fine but sometimes this code does't redirect to the other page....i don't know the reason why, Please tell me the exact reason

Is Typed DataSet is a good Approach

I want to develope a big web application, I want to know is that a good approach to use Typed DataSet in the DataAccess Layer
or
In which situations, we should use Typed DataSet and what are the benefits and drawbacks by using this approach