VB.Net中的WebBrowser.Refresh问题

I'm working on a webcrawler in VB.net, and using the System.Forms.WebBrowser object for handling navigation on sites that use javascript or form posts, but I'm having a problem. When I navigate backwards (WebBrowser.GoBack()) to a page that was loaded with a form post, the page has expired and I have to do a refresh to resend the request. When I call a refresh (WebBrowser.Refresh()), a dialog box pops up to confirm. Is there a way I can get around this modal dialog in code? Thanks!I'm working on a webcrawler in VB.net, and usin