Interesting stuff. None of it appears to directly apply, but I can't be quite certain. The last article lists a series of potential causes for this issue, and I think I can rule out all but one. On the other hand, the table is linked to a second table that uses a unique ID primary key, and the first link suggests that that could be the source of the problem. However, it has happened only one time in three years across a few dozen installations, so that seem unlikely to be the cause.

It is likely that no specific cause will ever be identified, but those links are suggestive.