Why is it that sometimes when you run a page from VWD Express, the page opens just fine, but other times, you get the "Page cannot be displayed" error?

For some reason, mine is doing that more and more lately. I have to keep doing it many times, then all of a sudden it will work.

Could someone please explain what is happening? This is getting frustrating and inhibits my progress through the book( Begining ASP.NET 2.0 )

Any help would be greatly appreciated.

Thank you!:)