1) If you are building a web part and  is crashing the webpage, here is a quick way to remove it and get the rest of the page working.Add contents=1 to for example, if the page url is http://axep/default.aspx then change it to http://axep/default.aspx?content=1 and it will bring up the web part page maintenance page and lists all the webparts that are used in that page and provides way to delete selected web parts , switch view or reset.

(2) If you are trying to access the SharePoint just with the site url without specifying default.aspx , for ex http://axep and instead of rendering the webpart page, if it gives a File download warning, check the Execute permission property of the IIS Web site. For the default page to be redirected from just the URL, the IIS web site should have execute permission  set to “Scripts and Executables”