Cannot use a leading .. to exit above the top directory.

Using Visual Web Developer to build aspx (c#) forms. When testing we were jumping up a level to reach the root 'App Data' folder, now we have gone live, we have done a find and replace for all the '../' throughout the site as the 'App Data' folder is now sat in the same folder as the web site. We are now getting the following error 'Cannot use a leading .. to exit above the top directory.' Would there be any other reason for this. Nowhere in the site is the tilde symbol used.

Here is the error:


[HttpException (0x80004005): Cannot use a leading .. to exit above the top directory.]
   System.Web.Util.UrlPath.ReduceVirtualPath(String path) +3626102
   System.Web.Util.UrlPath.Reduce(String path) +84
   System.Web.Util.UrlPath.Combine(String appPath, String basepath, String relative) +326
   System.Web.VirtualPath.Combine(VirtualPath relativePath) +166
   System.Web.HttpRequest.MapPath(VirtualPath virtualPath, VirtualPath baseVirtualDir, Boolean allowCrossAppMapping) +84
   System.Web.HttpServerUtility.MapPath(String path) +106
   Free_Business_Rates_Audit2.btnSend_Click(Object sender, EventArgs e) +51
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +105
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +107
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +7
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +11
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1746Start Free Trial