Strange error in ASP.NET
<p>Every once in a while I get about 10 - 20 identical errors on my asp.net app.  It's always the same, and I'm wondering if it is someone trying to hack in (it happens about once a month).</p>

<blockquote>
  <p><strong>Source:</strong> System.Web</p>
  
  <p><strong>Message:</strong> The file '/~/Default.aspx' does not exist.</p>
  
  <p><strong>User IP:</strong> 89.122.29.80</p>
  
  <p><strong>User Browser:</strong> Unknown 0.0</p>
  
  <p><strong>User OS:</strong> Unknown</p>
  
  <p><strong>Stack trace:</strong>    at
  System.Web.UI.Util.CheckVirtualFileExists(VirtualPath
  virtualPath)  at
  System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath
  virtualPath, Boolean noBuild, Boolean
  allowCrossApp, Boolean
  allowBuildInPrecompile)  at
  System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext
  context, VirtualPath virtualPath,
  Boolean noBuild, Boolean
  allowCrossApp, Boolean
  allowBuildInPrecompile)  at
  System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath
  virtualPath, HttpContext context,
  Boolean allowCrossApp, Boolean
  noAssert)  at
  System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath
  virtualPath, Type requiredBaseType,
  HttpContext context, Boolean
  allowCrossApp, Boolean noAssert)  at
  System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext
  context, String requestType,
  VirtualPath virtualPath, String
  physicalPath)  at
  System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(HttpContext
  context, String requestType,
  VirtualPath virtualPath, String
  physicalPath)  at
  System.Web.HttpApplication.MapHttpHandler(HttpContext
  context, String requestType,
  VirtualPath path, String
  pathTranslated, Boolean useAppConfig) 
  at
  System.Web.HttpApplication.MapHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at
  System.Web.HttpApplication.ExecuteStep(IExecutionStep
  step, Boolean completedSynchronously)</p>
</blockquote>

<p>why on earth would someone be trying to access "/~/Default.aspx" ?</p>
