error on edit - field body doesn't have a default value - find lost page again?

Running Drupal 6.10 on IIS 7. During a standard page edit, received the following PHP error (replaced elements indicated by [--]):

Field 'body'; doesn't have a default value query: INSERT INTO node_revisions (nid, uid, title, teaser, log, timestamp, format) VALUES (644, 4, '[--correct title of page appears here--]';, '', 'Added PDF of full paper.', 1242321716, 0) in [--path to includes--]\common.inc on line 3422.

And now the page does not show up in Drupal at all: the path alias returns a page-not-found and so does the actual node where that the page originates from.

In the MySQL db, I can find the node in the "node" table, and under nid it shows 644 (the correct node) but under vid it shows 0 instead of a number, whereas all the others I see have a number showing for vid. I've no idea what that means or whether there is a way for me to fiddle with this or any other table directly to bring the page back again.

Can I recover the lost page somehow and make it show up again via the regular Drupal editing interface (published or not)?

I'm using the diff module, and I thought perhaps I can pull data out of that somehow if necessary, but I wouldn't know where to go. And the specific edit that resulted in the error does not show up in the "node_revisions" table. Currently when I try to pull up the node or page alias all I get is a page not found so I can't revert whatever changes were made. Not all my modules are up-to-date, but the diff module is at 6.x-2.0. I assume there is no point in trying to troubleshoot the error itself until after I update everything to current versions and then the error appears again.

Phil.