BuddyPress.org

The reason Mercime asked you to deactivate BP was to establish whether blogs worked with WP, blogs are a feature of WP rather than BP and it’s important before running BP or attempting to troubleshoot issues that it’s established everything is working properly with plain vanilla WP.

You need to switch to a NON BP theme if you have disabled BP. Select the default twentyten theme or whatever default theme is installed for WP and confirm whether blogs work correctly.