[support] Cannot edit node after upgrading to Drupal 6

Hello Drupal Community, I upgraded my blog from Drupal 5 to Drupal 6, after the upgrade there was a lot of changes I made to the my blog like path of the images I used in my blog and some css styles. When I tried to update some nodes using the new path of the images and css styles, it gives me error 406. I can edit the node but everytime I hit the preview and save button, the page will then redirected to this error: The page you requested does not exist. For your convenience, a search was performed using the query /406 shtml/. Please take note that I'm using search 404 module. I don't know what seems to be the problem causing drupal to behave like this. Please help me. Regards, Richard R. Cahilig