I don't know exactly what's wrong ever since I have migrated to my new server earlier this month. I am having 404 errors in webmaster tools for the threads and posts. The 404 error was reported yesterday as well.
I just tried to visit one of the link and it was accessible by guests there was no problem in that. Sitemaps don't show any error around 40 sitemaps are submitted to google for my vB forum (automated sitemap generation using a plugin by vbSeo using it for over 2 years now)
can some one shed some light on what could be happening and how to check that so that the problem doesn't repeat as ever since this started happening there has been 70% search engine visitors drops to the forum ?