1. Truncate all of these tables:
Code:
    address_book
    customers
    customers_info
    email_archive
    products_notifications
    customers_basket
    customers_basket_attributes
    files_uploaded
    orders
    orders_products
    orders_products_attributes
    orders_products_download
    orders_status_history
    orders_total
    paypal
    paypal_payment_status_history
    paypal_session
    paypal_testing
    admin_activity_log
    authorizenet
    banners_history
    counter
    counter_history
    coupon_email_track
    coupon_redeem_track
    email_archive
    coupon_gv_customer
    coupon_gv_queue
2. Reset the products_viewed column to 0 in the products_description table.