I am having problems using HttpContext.Current.Request.Url.Host.

I have some code that does this...

if (HttpContext.Current != null)
               {

                   subdomain = HttpContext.Current.Request.Url.Host;

               }

Now if I put a break point on the if statement I get this error for the
HttpContext.Current.Request.  Request: 'HttpContext.Current.Request' threw
an exception of type 'System.Web.HttpException'

Now if I comment out the subdomain = HttpContext.Current.Request.Url.Host;
and stop at the same break point it works fine.

Now this seems to be a problem with the 3.5 framework because after I
installed it, this code seemed to not work any more.

Any idea's?

TIA,
Brett