Not able to post recipe after upgrading from D6.22 to D7.10

Hi

I was forced by a number of factors to upgrade a D6.22 site to D7.10.
Most of the process went well, also wit regard to the recipe module. Apart from the images, provided by the node images module, not in D7 & video field (emfield module), everything seems to work well, with the recipe displayed. I am having to re-insert videos & I'm yet to find a solution for the images.

The main problem, though is with creating content.
When I create a recipe & submit, I get this error:

    Notice: Undefined property: stdClass::$fid in file_usage_add() (line 657 of /home/que1/public_html/abc/includes/file.inc).
    PDOException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'fid' cannot be null: INSERT INTO {file_usage} (fid, module, type, id, count) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] => [:db_insert_placeholder_1] => file [:db_insert_placeholder_2] => node [:db_insert_placeholder_3] => 544 [:db_insert_placeholder_4] => 1 ) in file_usage_add() (line 664 of /home/que1/public_html/abc/includes/file.inc).

The website encountered an unexpected error. Please try again later. 

The recipe is apparently posted BUT there is this other error message, above it:

Notice: Undefined property: stdClass::$comment_count in comment_node_page_additions() (line 727 of /home/que1/public_html/abc/modules/comment/comment.module).

How can this be solved?
[I'm not a coder. :(]

I otherwise followed the instructions in the D7 readme for upgrading, such as disabling ALL non-core modules, etc.

I would be grateful for any help to solve this, because I'm in a sort of trap & cannot revert to D6.

Thank you.