Problem with updating posts via resetting date/time

At the outset – yes – I am running an older version of WP (2.12) for a number of reasons, not the least of which is I am unwilling to go through the hassles of updating and redoing my customizations.

To the problem, I have been using the reset date and time option when posting to put updates on posts to the current date and time. The last few times, though, have resulted in the post disappearing into thin air, in it’s entirely. Gone. Poof. All I did was change the date and time of the old post to the current date and time – which should have placed the post at the top of my blog.

I can think of no explanation why this is all of a sudden behaving like this. I haven’t used the function in a while, but never had this problem previously that I recall. Is there something else I should be doing other than clicking the “reset date/time” box and changing the date and date below?